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Section 1: DEFM14A (DEFM14A)


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UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of
the Securities Exchange Act of 1934 (Amendment No.          )

Filed by the Registrant ý

Filed by a Party other than the Registrant o

Check the appropriate box:

o

 

Preliminary Proxy Statement

o

 

Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))

ý

 

Definitive Proxy Statement

o

 

Definitive Additional Materials

o

 

Soliciting Material under §240.14a-12

 

ATWOOD OCEANICS, INC.

(Name of Registrant as Specified In Its Charter)

 

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check the appropriate box):

ý

 

No fee required.

o

 

Fee computed on table below per Exchange Act Rules 14a-6(i)(1) and 0-11.
    (1)   Title of each class of securities to which transaction applies:
        
 
    (2)   Aggregate number of securities to which transaction applies:
        
 
    (3)   Per unit price or other underlying value of transaction computed pursuant to Exchange Act Rule 0-11 (set forth the amount on which the filing fee is calculated and state how it was determined):
        
 
    (4)   Proposed maximum aggregate value of transaction:
        
 
    (5)   Total fee paid:
        
 

o

 

Fee paid previously with preliminary materials.

o

 

Check box if any part of the fee is offset as provided by Exchange Act Rule 0-11(a)(2) and identify the filing for which the offsetting fee was paid previously. Identify the previous filing by registration statement number, or the Form or Schedule and the date of its filing.

 

 

(1)

 

Amount Previously Paid:
        
 
    (2)   Form, Schedule or Registration Statement No.:
        
 
    (3)   Filing Party:
        
 
    (4)   Date Filed:
        
 

LOGO   LOGO


August 18, 2017

MERGER PROPOSED—YOUR VOTE IS VERY IMPORTANT

        On May 29, 2017, Echo Merger Sub LLC ("Merger Sub"), a wholly owned subsidiary of Ensco plc ("Ensco"), agreed to merge with and into Atwood Oceanics, Inc. ("Atwood"), with Atwood surviving the merger as a wholly owned subsidiary of Ensco. We are sending you this joint proxy statement/prospectus to ask you to vote in favor of this merger and other matters.

        If the merger is completed, each Atwood shareholder will be entitled to receive 1.60 Class A ordinary shares, nominal value $0.10 per share, of Ensco (the "Ensco Class A ordinary shares") for each share of common stock, par value $1.00 per share, of Atwood (the "Atwood common stock") owned by such Atwood shareholder. Following the completion of the merger, it is anticipated that persons who were shareholders of Ensco and Atwood immediately prior to the merger will own approximately 69% and 31% of the combined company, respectively.

        Ensco Class A ordinary shares are quoted on the New York Stock Exchange ("NYSE") under the symbol "ESV," and Atwood common stock is quoted on the NYSE under the symbol "ATW." The market prices of both Ensco Class A ordinary shares and Atwood common stock will fluctuate before the merger, and you should obtain current stock price quotations for the Ensco Class A ordinary shares and the Atwood common stock.

        Your vote is very important.    We cannot complete the merger unless the Ensco shareholders vote to approve the issuance of Ensco Class A ordinary shares pursuant to the merger agreement and the Atwood shareholders vote to approve the merger agreement and the transactions contemplated thereby, including the merger.

        This document is a prospectus relating to the Ensco Class A ordinary shares to be issued to Atwood shareholders pursuant to the merger and a joint proxy statement for Ensco and Atwood to solicit proxies for their respective meetings of shareholders. It contains answers to frequently asked questions and a summary of the important terms of the merger, the merger agreement and related transactions, followed by a more detailed discussion.

        Please carefully read this entire document, including "Risk Factors" beginning on page 19, for a discussion of the risks relating to the merger and the combined company following the merger.

        None of the Securities and Exchange Commission, any state securities regulatory authority or the U.K. Financial Conduct Authority (the "FCA") has approved or disapproved of the merger or the securities to be issued under this joint proxy statement/prospectus or has passed upon the adequacy or accuracy of the disclosure in this joint proxy statement/prospectus. Any representation to the contrary is a criminal offense.

        For the avoidance of doubt, this joint proxy statement/prospectus is not intended to be, and is not, a prospectus for the purposes of the Prospectus Rules made under Part 6 of the U.K. Financial Services and Markets Act 2000 (as set out in the U.K. FCA's Handbook).

   

        The date of this joint proxy statement/prospectus is August 18, 2017, and it is first being mailed or otherwise delivered to Ensco shareholders and Atwood shareholders on or about August 21, 2017.


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LOGO

Ensco plc
6 Chesterfield Gardens
London, W1J 5BQ, United Kingdom
44 (0) 20 7659 4660


NOTICE OF GENERAL MEETING OF SHAREHOLDERS
TO BE HELD ON OCTOBER 5, 2017

To the Shareholders of Ensco plc:

        A general meeting of the shareholders of Ensco plc ("Ensco") will be held at the offices of Slaughter and May, One Bunhill Row, London EC1Y 8YY, England, at 3:00 P.M. (London time) on October 5, 2017 (the "Ensco general meeting").

        You will be asked to consider and pass the resolutions below. The full text of each resolution is set out in the joint proxy statement/prospectus accompanying this notice.

ORDINARY RESOLUTIONS

1.
Ensco Merger Consideration Proposal: To authorize, in addition to all subsisting authorities, the allotment and issuance of Ensco Class A ordinary shares, nominal value $0.10 per share (the "Ensco Class A ordinary shares"), to shareholders of Atwood Oceanics, Inc. ("Atwood"), pursuant to the Agreement and Plan of Merger, dated as of May 29, 2017, by and among Ensco, Echo Merger Sub LLC, a wholly owned subsidiary of Ensco ("Merger Sub"), and Atwood, as such agreement may be amended from time to time (the "merger agreement"), which provides for, among other things, the merger of Merger Sub with and into Atwood (the "merger"), with Atwood surviving the merger as a wholly owned subsidiary of Ensco.

2.
Ensco General Allotment Authority Increase Proposal: To authorize, in addition to all subsisting authorities, the allotment and issuance up to a nominal amount of Ensco Class A ordinary shares, which, together with the nominal amount of shares of Ensco authorized to be allotted and issued pursuant to paragraph (A) of resolution 11 passed at the annual general meeting of Ensco shareholders held on May 22, 2017 (the "Ensco 2017 Annual General Meeting"), represents approximately 33% of the expected enlarged share capital of Ensco immediately following the completion of the merger, and up to a further same nominal amount of Ensco Class A ordinary shares in connection with a pre-emptive offering of shares.

SPECIAL RESOLUTIONS

3.
Ensco General Disapplication of Pre-emptive Rights Proposal: To authorize, in addition to all subsisting authorities, the allotment and issuance up to a nominal amount of Ensco Class A ordinary shares for cash on a non-pre-emptive basis, which, together with the nominal amount of shares in Ensco authorized to be allotted and issued for cash on a non-pre-emptive basis pursuant to resolution 12 passed at the Ensco 2017 Annual General Meeting, represents approximately 5% of the expected enlarged share capital of Ensco immediately following the completion of the merger.

4.
Ensco Specified Disapplication of Pre-emptive Rights Proposal: To authorize, in addition to all subsisting authorities, the allotment and issuance up to a nominal amount of Ensco Class A ordinary shares for cash on a non-pre-emptive basis, which, together with the nominal amount of shares in Ensco authorized to be allotted and issued for cash on a non-pre-emptive basis pursuant to resolution 13 passed at the Ensco 2017 Annual General Meeting, represents approximately 5%

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        As a U.K. company publicly traded on the New York Stock Exchange (the "NYSE"), Ensco shareholder approval of the Ensco Merger Consideration Proposal is subject to both the shareholder approval requirements under the U.K. Companies Act 2006 (the "Companies Act 2006") and NYSE rules. The Ensco Merger Consideration Proposal is being proposed as an ordinary resolution. Assuming a quorum is present, such proposal will be approved for the purposes of the Companies Act 2006 and NYSE rules if a majority of the votes cast are cast in favor thereof. In addition, the Ensco General Allotment Authority Increase Proposal will be proposed as an ordinary resolution and, assuming a quorum is present, will be approved if a majority of the votes cast are cast in favor thereof. Each of the Ensco General Disapplication of Pre-emptive Rights Proposal and the Ensco Specified Disapplication of Pre-emptive Rights Proposal will be proposed as a special resolution, which means, assuming a quorum is present, each such proposal will be approved if at least 75% of the votes cast are cast in favor thereof.

        Approval of the Ensco Merger Consideration Proposal is required for completion of the merger. Approval of the other Ensco proposals set forth above is not required in order to complete the merger.

        The board of directors of Ensco recommends that the Ensco shareholders vote:

        This joint proxy statement/prospectus and accompanying proxy card are being sent or given to shareholders on or about August 21, 2017. Only Ensco shareholders of record at the close of business in London on August 23, 2017, the record date for the Ensco general meeting, are entitled to receive notice of, attend and vote at the Ensco general meeting or, subject to the Ensco Articles of Association, any adjournments or postponements of the Ensco general meeting.

        Please review the joint proxy statement/prospectus accompanying this notice for more complete information regarding the merger and the Ensco general meeting, as well as the full text of all of the resolutions to be proposed at the Ensco general meeting.

        In accordance with provisions in the Companies Act 2006 and the Ensco Articles of Association, a shareholder of record is entitled to appoint another person as his or her proxy to exercise all or any of his or her rights to attend, speak and vote at the Ensco general meeting and to appoint more than one proxy in relation to the Ensco general meeting (provided that each proxy is appointed to exercise the rights attached to a different share or shares held by him or her). Such proxy need not be a shareholder of record.

        If you received a proxy card by mail, you may submit your proxy by completing, signing, dating and returning your proxy card in the envelope provided. Submitting a proxy will assure that your vote is counted at the meeting if you do not attend in person. If your Ensco Class A ordinary shares are held in "street name" by your broker, bank, trust or other nominee, only that holder can vote your Ensco Class A ordinary shares and the vote cannot be cast unless you provide instructions to your broker, bank, trust or other nominee or obtain a legal proxy from your broker, bank, trust or other nominee. You should follow the directions provided by your broker, bank, trust or other nominee regarding how to instruct such person to vote your Ensco Class A ordinary shares. If you have returned a proxy card or otherwise voted, you may revoke prior instructions and cast your vote by following the procedures described in the joint proxy statement/prospectus.


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YOUR VOTE IS IMPORTANT

        Whether or not you plan to attend the general meeting, please submit a proxy or voting instruction card as soon as possible. For specific instructions on voting, please refer to the joint proxy statement/prospectus accompanying this notice of meeting or the proxy card included with the proxy voting materials.

 
   

 

 

BY ORDER OF THE BOARD OF DIRECTORS,

 

 

SIGNATURE

 

 

Michael T. McGuinty
    Senior Vice President, General Counsel and Secretary

 

 

August 18, 2017

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LOGO

Atwood Oceanics, Inc.
15011 Katy Freeway, Suite 800
Houston, Texas 77094
(281) 749-7800


NOTICE OF SPECIAL MEETING OF SHAREHOLDERS
TO BE HELD ON OCTOBER 5, 2017

To the Shareholders of Atwood Oceanics, Inc.:

        A special meeting of the shareholders of Atwood Oceanics, Inc. ("Atwood") will be held at 15011 Katy Freeway, First Floor, Houston, Texas 77094, at 9:00 A.M. (Houston time) on October 5, 2017 (the "Atwood special meeting") to consider and vote upon the following proposals:

1.
Atwood Merger Proposal: To approve the Agreement and Plan of Merger, dated as of May 29, 2017, by and among Ensco plc ("Ensco"), Echo Merger Sub LLC, a wholly owned subsidiary of Ensco ("Merger Sub"), and Atwood, as such agreement may be amended from time to time (the "merger agreement"), and the transactions contemplated thereby, including the merger of Merger Sub with and into Atwood (the "merger"), with Atwood surviving the merger as a wholly owned subsidiary of Ensco;

2.
Atwood Compensatory Proposal: To approve an advisory (non-binding) vote on the specified compensation that may be received by Atwood's named executive officers in connection with the transactions contemplated by the merger agreement, including the merger; and

3.
Atwood Adjournment Proposal: To approve the adjournment of the Atwood special meeting, if necessary or advisable, to solicit additional proxies in favor of the Atwood Merger Proposal or take any other action in connection with the merger agreement.

        The Atwood Merger Proposal requires the approval of Atwood shareholders holding at least two-thirds of the Atwood common stock entitled to vote thereon pursuant to the requirements of the Texas Business Organizations Code. Assuming a quorum is present, the Atwood Compensatory Proposal requires the approval of a majority of votes cast by the Atwood shareholders present, in person or by proxy, at the Atwood special meeting. The vote to approve the Atwood Compensatory Proposal is not a condition to the completion of the merger, and the vote of Atwood's shareholders on such proposal is advisory in nature and will not be binding on Ensco or Atwood. Accordingly, regardless of the outcome of the Atwood Compensatory Proposal, if the Atwood Merger Proposal is approved and the merger is completed, specified compensation may be paid to Atwood's named executive officers. Whether or not a quorum is present, the Atwood Adjournment Proposal requires the approval of a majority of votes cast by the Atwood shareholders present, in person or by proxy, at the Atwood special meeting.

        Approval of the Atwood Merger Proposal is required for completion of the merger. Approval of the other Atwood proposals set forth above is not required in order to complete the merger.

        The board of directors of Atwood recommends that the Atwood shareholders vote:


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        This joint proxy statement/prospectus and accompanying proxy card are being sent or given to shareholders on or about August 21, 2017. Only Atwood shareholders of record at the close of business on August 23, 2017, the record date for the Atwood special meeting, are entitled to notice of, and to vote at, the Atwood special meeting and any adjournments or postponements of the Atwood special meeting.

        Please review the joint proxy statement/prospectus accompanying this notice for more complete information regarding the merger and the Atwood special meeting.

        If you received a proxy card by mail, you may submit your proxy by completing, signing, dating and returning your proxy card in the envelope provided. Submitting a proxy will assure that your vote is counted at the meeting if you do not attend in person. If your shares of Atwood common stock are held in "street name" by your broker or other nominee, only that holder can vote your shares of Atwood common stock and the vote cannot be cast unless you provide instructions to your broker or obtain a legal proxy from your broker. You should follow the directions provided by your broker regarding how to instruct your broker to vote your shares of Atwood common stock. If you have returned a proxy card or otherwise voted, you may revoke prior instructions and cast your vote by following the procedures described in the joint proxy statement/prospectus.


YOUR VOTE IS IMPORTANT

        Whether or not you plan to attend the Atwood special meeting, please submit a proxy or vote instruction card as soon as possible. For specific instructions on voting, please refer to the joint proxy statement/prospectus accompanying this notice of meeting or the proxy card included with the proxy voting materials.

    BY ORDER OF THE BOARD OF DIRECTORS,

 

 

SIGNATURE

Walter A. Baker
Senior Vice President, General Counsel
and Corporate Secretary

 

 

August 18, 2017

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REFERENCES TO ADDITIONAL INFORMATION

        This joint proxy statement/prospectus incorporates by reference important business and financial information about Ensco plc ("Ensco") and Atwood Oceanics, Inc. ("Atwood") from documents that are not included in or delivered with this joint proxy statement/prospectus. See "Where You Can Find More Information."

        You can obtain documents incorporated by reference in this joint proxy statement/prospectus, other than certain exhibits to those documents, by requesting them in writing or by telephone from the appropriate company at the following addresses:

Ensco plc
Attn: Investor Relations
5847 San Felipe, Suite 3300
Houston, Texas 77057
(713) 789-1400

 

Atwood Oceanics, Inc.
Attn: Investor Relations
15011 Katy Freeway, Suite 800
Houston, Texas 77094
(281) 749-7800

        You will not be charged for any of these documents that you request. To receive timely delivery of the requested documents in advance of the general meeting of Ensco shareholders (the "Ensco general meeting") or the special meeting of Atwood shareholders (the "Atwood special meeting"), you should make your request no later than September 28, 2017.


ABOUT THIS JOINT PROXY STATEMENT/PROSPECTUS

        This joint proxy statement/prospectus, which forms part of a registration statement on Form S-4 filed with the Securities and Exchange Commission (the "SEC") by Ensco (File No. 333-218808), constitutes a prospectus of Ensco under Section 5 of the Securities Act of 1933, as amended (the "Securities Act"), with respect to the Ensco Class A ordinary shares, nominal value $0.10 per share (the "Ensco Class A ordinary shares"), to be issued to holders of Atwood common stock, par value $1.00 per share (the "Atwood common stock"), pursuant to the merger agreement.

        This joint proxy statement/prospectus also constitutes a joint proxy statement under Section 14(a) of the Securities Exchange Act of 1934, as amended (the "Exchange Act"). It also includes a notice of meeting with respect to the Ensco general meeting, at which Ensco shareholders will be asked to consider and vote upon, among other matters, a proposal to approve the allotment and issuance of Ensco Class A ordinary shares to Atwood shareholders pursuant to the merger agreement, and a notice of the Atwood special meeting, at which Atwood shareholders will be asked to consider and vote upon, among other matters, a proposal to approve the merger agreement and the transactions contemplated thereby, including the merger.

        You should rely only on the information contained in or incorporated by reference into this joint proxy statement/prospectus. No one has been authorized to provide you with information that is different from that contained in, or incorporated by reference into, this joint proxy statement/prospectus. This joint proxy statement/prospectus is dated August 18, 2017. The information contained in this joint proxy statement/prospectus is accurate only as of that date or, in the case of information in a document incorporated by reference, as of the date of such document, unless the information specifically indicates that another date applies. Neither the mailing of this joint proxy statement/prospectus to Ensco shareholders or Atwood shareholders nor the issuance of Ensco Class A ordinary shares to Atwood shareholders pursuant to the merger agreement will create any implication to the contrary.

        This joint proxy statement/prospectus does not constitute an offer to sell, or a solicitation of an offer to buy, any securities, or the solicitation of a proxy, in any jurisdiction in which or from any person to whom it is unlawful to make any such offer or solicitation in such jurisdiction.

        The information concerning Ensco contained or incorporated by reference in this joint proxy statement/prospectus has been provided by Ensco, and the information concerning Atwood contained or incorporated by reference in this joint proxy statement/prospectus has been provided by Atwood.


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        This joint proxy statement/prospectus contains a description of the representations and warranties that each of Ensco and Atwood made to the other in the merger agreement. Representations and warranties made by Ensco, Atwood and other applicable parties are also set forth in contracts and other documents (including the merger agreement) that are attached or filed as exhibits to this joint proxy statement/prospectus or are incorporated by reference into this joint proxy statement/prospectus. These representations and warranties were made as of specific dates, may be subject to important qualifications and limitations agreed to between the parties in connection with negotiating the terms of the agreement, and may have been included in the agreement for the purpose of allocating risk between the parties rather than to establish matters as facts. These materials are included or incorporated by reference only to provide you with information regarding the terms and conditions of the agreements, and not to provide any other factual information regarding Ensco, Atwood or their respective businesses. Accordingly, the representations and warranties and other provisions of the merger agreement and the other agreements incorporated by reference herein should not be read alone, but instead should be read only in conjunction with the other information provided elsewhere in this joint proxy statement/prospectus or incorporated by reference herein, as applicable.


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QUESTIONS AND ANSWERS ABOUT THE MEETINGS

    iii  

SUMMARY

    1  

SELECTED HISTORICAL CONSOLIDATED FINANCIAL DATA OF ENSCO

    14  

SELECTED HISTORICAL CONSOLIDATED FINANCIAL DATA OF ATWOOD

    16  

UNAUDITED COMPARATIVE PER SHARE DATA

    17  

COMPARATIVE MARKET PRICES AND DIVIDENDS

    18  

RISK FACTORS

    19  

RISKS RELATING TO THE MERGER

    19  

RISKS RELATING TO THE COMBINED COMPANY FOLLOWING THE MERGER

    24  

RISKS INHERENT IN AN INVESTMENT IN ENSCO

    27  

CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTS

    30  

THE ENSCO GENERAL MEETING

    33  

ENSCO PROPOSAL 1—MERGER CONSIDERATION PROPOSAL

    38  

ENSCO PROPOSAL 2—GENERAL ALLOTMENT AUTHORITY INCREASE PROPOSAL

    39  

ENSCO PROPOSALS 3 AND 4—DISAPPLICATION OF PRE-EMPTIVE RIGHTS PROPOSALS

    42  

THE ATWOOD SPECIAL MEETING

    45  

THE MERGER

    49  

BACKGROUND OF THE MERGER

    49  

ENSCO'S REASONS FOR THE MERGER; RECOMMENDATION OF THE ENSCO BOARD OF DIRECTORS

    57  

ATWOOD'S REASONS FOR THE MERGER; RECOMMENDATION OF THE ATWOOD BOARD OF DIRECTORS

    59  

OPINION OF FINANCIAL ADVISOR TO ENSCO

    63  

OPINION OF FINANCIAL ADVISOR TO ATWOOD

    75  

CERTAIN UNAUDITED FINANCIAL FORECASTS PREPARED BY THE MANAGEMENT OF ENSCO

    84  

CERTAIN UNAUDITED FINANCIAL FORECASTS PREPARED BY THE MANAGEMENT OF ATWOOD

    87  

BOARD OF DIRECTORS AND EXECUTIVE OFFICERS OF ENSCO FOLLOWING THE MERGER

    91  

PUBLIC TRADING MARKETS

    91  

NO APPRAISAL OR DISSENTERS' RIGHTS

    91  

ACCOUNTING TREATMENT OF THE MERGER

    92  

REGULATORY APPROVALS REQUIRED FOR THE MERGER

    92  

LITIGATION RELATING TO THE MERGER

    92  

ATWOOD'S DIRECTORS AND OFFICERS HAVE FINANCIAL INTERESTS IN THE MERGER

    93  

THE MERGER AGREEMENT

    99  

TERMS OF THE MERGER

    99  

CLOSING AND EFFECTIVE TIME OF THE MERGER

    99  

CONSIDERATION TO BE RECEIVED IN THE MERGER

    99  

TREATMENT OF ATWOOD EQUITY-BASED AWARDS

    100  

CONVERSION OF SHARES; EXCHANGE OF CERTIFICATES

    100  

REPRESENTATIONS AND WARRANTIES

    101  

DEFINITION OF MATERIAL ADVERSE EFFECT

    102  

COVENANTS AND AGREEMENTS

    103  

AGREEMENT NOT TO SOLICIT OTHER OFFERS

    109  

EXPENSES AND FEES

    112  

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EMPLOYEE MATTERS

    112  

INDEMNIFICATION AND INSURANCE

    113  

CONDITIONS TO COMPLETE THE MERGER

    114  

TERMINATION OF THE MERGER AGREEMENT

    114  

TERMINATION FEES AND EXPENSE REIMBURSEMENT

    116  

AMENDMENT, WAIVER, EXTENSION AND SPECIFIC PERFORMANCE OF THE MERGER AGREEMENT

    117  

UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL STATEMENTS OF ENSCO

    118  

MATERIAL UNITED STATES FEDERAL INCOME TAX CONSEQUENCES OF THE MERGER

    130  

TAX CONSEQUENCES OF THE MERGER TO ATWOOD AND ENSCO

    131  

TAX CONSEQUENCES OF THE MERGER TO ATWOOD SHAREHOLDERS

    132  

TAX CONSEQUENCES OF HOLDING ENSCO CLASS A ORDINARY SHARES TO U.S. HOLDERS

    136  

TAX CONSEQUENCES OF HOLDING ENSCO CLASS A ORDINARY SHARES TO NON-U.S. HOLDERS

    137  

ATWOOD PROPOSAL 2—COMPENSATORY PROPOSAL

    139  

ATWOOD PROPOSAL 3—ADJOURNMENT PROPOSAL

    140  

INFORMATION ABOUT THE COMPANIES

    141  

ENSCO PLC

    141  

ECHO MERGER SUB LLC

    141  

ATWOOD OCEANICS, INC. 

    141  

DESCRIPTION OF ENSCO CLASS A ORDINARY SHARES

    142  

COMPARISON OF RIGHTS OF ATWOOD SHAREHOLDERS AND ENSCO SHAREHOLDERS

    148  

LEGAL MATTERS

    176  

EXPERTS

    176  

ENSCO 2018 ANNUAL SHAREHOLDER MEETING AND SHAREHOLDER PROPOSALS

    176  

ATWOOD 2018 ANNUAL SHAREHOLDER MEETING AND SHAREHOLDER PROPOSALS

    177  

SHAREHOLDERS SHARING AN ADDRESS

    177  

COMMISSION POSITION ON INDEMNIFICATION FOR SECURITIES ACT LIABILITIES

    178  

WHERE YOU CAN FIND MORE INFORMATION

    178  

ANNEX A: AGREEMENT AND PLAN OF MERGER

   
A-1
 

ANNEX B: OPINION OF MORGAN STANLEY & CO. LLC

    B-1  

ANNEX C: OPINION OF GOLDMAN SACHS & CO. LLC

    C-1  

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QUESTIONS AND ANSWERS ABOUT THE MEETINGS

        The following are some questions that Ensco shareholders and Atwood shareholders may have regarding the proposals being considered at the Ensco general meeting and the Atwood special meeting and brief answers to those questions. Ensco and Atwood urge you to read carefully this entire joint proxy statement/prospectus, including the annexes, and the other documents to which this joint proxy statement/prospectus refers or incorporates by reference because the information in this section does not provide all the information that might be important to you.

Q:
What is the merger for which I am being asked to vote?

A:
Ensco, Echo Merger Sub LLC, a wholly owned subsidiary of Ensco ("Merger Sub"), and Atwood have entered into an Agreement and Plan of Merger, dated as of May 29, 2017 (the "merger agreement"), pursuant to which Merger Sub will merge with and into Atwood (the "merger"), with Atwood surviving the merger as a wholly owned subsidiary of Ensco. Each issued and outstanding share of Atwood common stock, par value $1.00 per share (the "Atwood common stock"), will be converted into the right to receive 1.60 (the "exchange ratio") Ensco Class A ordinary shares, nominal value $0.10 per share (the "Ensco Class A ordinary shares"), as described under "The Merger Agreement—Consideration To Be Received in the Merger." A copy of the merger agreement is attached as Annex A to this joint proxy statement/prospectus.

Q:
Why are Ensco and Atwood proposing the merger?

A:
The board of directors of Ensco (the "Ensco Board") and the board of directors of Atwood (the "Atwood Board") believe that the merger will benefit Ensco shareholders and Atwood shareholders, respectively, by creating a leading global offshore drilling company given the complementary fleet composition, geographic scope and customer bases of the two companies. To review the reasons for the merger in greater detail, see "The Merger—Ensco's Reasons for the Merger; Recommendation of the Ensco Board of Directors" beginning on page 57 and "The Merger—Atwood's Reasons for the Merger; Recommendation of the Atwood Board of Directors" beginning on page 59.

Q:
What are the Ensco shareholders being asked to approve?

A:
Ensco shareholders are being asked to approve the authorization of, in addition to all subsisting authorities:

1.
Ensco Merger Consideration Proposal: The allotment and issuance of Ensco Class A ordinary shares to Atwood shareholders pursuant to the merger agreement;

2.
Ensco General Allotment Authority Increase Proposal: The allotment and issuance up to a nominal amount of Ensco Class A ordinary shares, which, together with the nominal amount of shares in Ensco authorized to be allotted and issued pursuant to paragraph (A) of resolution 11 passed at the annual general meeting of Ensco shareholders held on May 22, 2017 (the "Ensco 2017 Annual General Meeting"), represents approximately 33% of the expected enlarged share capital of Ensco immediately following the completion of the merger, and up to a further same nominal amount of Ensco Class A ordinary shares in connection with a pre-emptive offering of shares;

3.
Ensco General Disapplication of Pre-emptive Rights Proposal: The allotment and issuance up to a nominal amount of Ensco Class A ordinary shares for cash on a non-pre-emptive basis, which, together with the nominal amount of shares in Ensco authorized to be allotted and issued for cash on a non-pre-emptive basis pursuant to resolution 12 passed at the Ensco 2017 Annual

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Q:
How does the Ensco Board recommend that Ensco shareholders vote?

A:
The Ensco Board has unanimously determined that the form, terms and provisions of the merger agreement and the transactions contemplated thereby, including the merger and the allotment and issuance of the Ensco Class A ordinary shares, are advisable, fair and reasonable to and in the best interests of Ensco and its shareholders and unanimously recommends that Ensco shareholders vote:

"FOR" the Ensco Merger Consideration Proposal;

"FOR" the Ensco General Allotment Authority Increase Proposal;

"FOR" the Ensco General Disapplication of Pre-Emptive Rights Proposal; and

"FOR" the Ensco Specified Disapplication of Pre-Emptive Rights Proposal.

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Q:
What are Atwood shareholders being asked to consider and approve?

A:
Atwood shareholders are being asked to consider and approve:

1.
Atwood Merger Proposal: The merger agreement and the transactions contemplated thereby, including the merger;

2.
Atwood Compensatory Proposal: An advisory (non-binding) vote on the specified compensation that may be received by Atwood's named executive officers in connection with the transactions contemplated by the merger agreement, including the merger; and

3.
Atwood Adjournment Proposal: The adjournment of the Atwood special meeting, if necessary or advisable, to solicit additional proxies in favor of the Atwood Merger Proposal or take any other action in connection with the merger agreement.
Q:
How does the Atwood Board recommend that Atwood shareholders vote?

A:
The Atwood Board has unanimously determined that the merger agreement and the transactions contemplated thereby, including the merger, are advisable and in the best interests of Atwood and its shareholders and unanimously recommends that Atwood shareholders vote:

"FOR" the Atwood Merger Proposal;

"FOR" the Atwood Compensatory Proposal; and

"FOR" the Atwood Adjournment Proposal.
Q:
When and where is the Ensco general meeting?

A:
The Ensco general meeting will be held at the offices of Slaughter and May, One Bunhill Row, London EC1Y 8YY, England, at 3:00 P.M. (London time) on October 5, 2017.

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Q:
When and where is the Atwood special meeting?

A:
The Atwood special meeting will be held at 15011 Katy Freeway, First Floor, Houston, Texas 77094, at 9:00 A.M. (Houston time) on October 5, 2017.

Q:
Who can attend and vote at the Ensco general meeting?

A:
All Ensco shareholders of record as of the close of business on August 23, 2017 (the "Ensco record date") are entitled to receive notice of, attend and vote at the Ensco general meeting. If you are an Ensco shareholder of record as of the close of business on the Ensco record date for the Ensco general meeting and plan to attend the Ensco general meeting, please bring the notice of meeting as your proof of ownership of Ensco Class A ordinary shares. If you are a "street name" holder of Ensco Class A ordinary shares and wish to attend the Ensco general meeting, you will need to bring evidence of your share ownership in the form of a recently dated letter from your broker, bank, trust or other nominee as of the Ensco record date and proof of your identity. On verification of such evidence, you will be admitted to the Ensco general meeting, but may not vote at the Ensco general meeting unless you hold a proxy from the shareholder of record. Each share is entitled to one vote at the Ensco general meeting, and there is no cumulative voting. In accordance with the Ensco Articles of Association, voting on all resolutions will be conducted on a poll and not on a show of hands.
Q:
Who can attend and vote at the Atwood special meeting?

A:
All Atwood shareholders of record as of the close of business on August 23, 2017 (the "Atwood record date") are entitled to receive notice of, attend and vote at the Atwood special meeting. If you are a "street name" holder of shares of Atwood common stock and wish to attend the Atwood special meeting, you will need to bring evidence of your share ownership in the form of a currently dated letter from your broker, bank, trust or other nominee and proof of your identity. On verification of such evidence, you will be admitted to the Atwood special meeting, but may not vote at the Atwood special meeting unless you are a shareholder of record or hold a proxy from a shareholder of record.

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Q:
If my Ensco Class A ordinary shares or Atwood common stock are held in "street name" by my broker, bank, trust or other nominee, will my broker, bank, trust or other nominee vote my Ensco Class A ordinary shares or Atwood common stock for me?

A:
If your shares are held in the name of a broker, bank, trust or other nominee as a custodian, you are a "street name" holder. Please follow the voting instructions provided by your broker, bank, trust or other nominee. Please note that you may not vote shares held in street name by returning a proxy card or voting instruction directly to Ensco or Atwood or by voting in person at the respective general or special meetings unless you provide a "legal proxy," which you must obtain from your broker, bank, trust or other nominee.
Q:
What are the effects of abstentions and broker non-votes at the meetings?

A:
An abstention occurs when a shareholder abstains from voting (either in person or by proxy) on one or more of the proposals. Broker non-votes occur when a broker, bank, trust or other nominee returns a proxy but does not have authority to vote on a particular proposal. You should therefore provide your broker, bank, trust or other nominee with instructions as to how to vote your Ensco Class A ordinary shares or Atwood common stock, as applicable.

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Q:
What happens if the merger is not completed?

A:
If the Ensco Merger Consideration Proposal is not approved by the Ensco shareholders, if the Atwood Merger Proposal is not approved by the Atwood shareholders or if the merger is not completed for any other reason, Atwood shareholders will not receive any Ensco Class A ordinary shares in consideration for their shares of Atwood common stock. Instead, Atwood will remain an independent public company and Atwood common stock will continue to be listed and traded on the NYSE. Under the merger agreement, Ensco may be required to pay Atwood a termination fee of $50 million (less any expenses previously reimbursed by Ensco) if the merger agreement is terminated under certain circumstances, and Atwood may be required to pay Ensco a termination fee of $30 million (less any expenses previously reimbursed by Atwood) if the merger agreement is terminated under certain circumstances. See "The Merger Agreement—Termination Fees and Expense Reimbursement" beginning on page 116.

Q:
Are there risks associated with the merger that I should consider in deciding how to vote?

A:
Yes. There are a number of risks related to the merger that are discussed in this joint proxy statement/prospectus and in other documents incorporated by reference. You should read carefully the detailed description of the risks associated with the merger and the operations of Ensco after the merger described in "Risk Factors" beginning on page 19.

Q:
Are Atwood shareholders entitled to appraisal or dissenters' rights?

A:
No. Atwood shareholders who dissent to the merger will not have rights to an appraisal of the fair value of their shares. Under the TBOC, shareholders generally have appraisal rights in the event of a merger or consolidation. However, these appraisal rights are not available if (i) the shares held by the shareholder are part of a class of shares listed on a national securities exchange or held of record by at least 2,000 holders, (ii) the shareholder is not required to accept for his or her shares any consideration that is different than the consideration to be provided to any other holder of shares of the same class held by the shareholder, and (iii) the shareholder is not required to accept any consideration other than shares of a corporation that satisfy the requirements in clause (i) above. Because Ensco Class A ordinary shares are listed on the NYSE, a national securities exchange, and are expected to continue to be so listed following the merger, and because the merger otherwise satisfies the foregoing requirements, Atwood shareholders will not be entitled to appraisal or dissenters' rights in the merger with respect to their shares of Atwood common stock.

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Q:
What do I need to do now?

A:
After you have carefully read this joint proxy statement/prospectus, please respond by completing, signing and dating your proxy card or voting instruction card, as applicable, and returning it in the enclosed postage-paid envelope or, if available, by submitting your proxy or voting instructions by telephone or through the Internet as soon as possible so that your Ensco Class A ordinary shares or your shares of Atwood common stock, as applicable, will be represented and voted at the Ensco general meeting or Atwood special meeting, as applicable.
Q:
How will my Ensco Class A ordinary shares be voted?

A:
All Ensco Class A ordinary shares entitled to vote and represented by properly completed proxies received prior to the Ensco general meeting, and not revoked, will be voted at the Ensco general meeting as instructed on the proxies. If you properly complete, sign and return a proxy card, but do not indicate how your Ensco Class A ordinary shares should be voted on a matter, the Ensco Class A ordinary shares represented by your proxy will be voted as the Ensco Board recommends and, therefore:

"FOR" the Ensco Merger Consideration Proposal;

"FOR" the Ensco General Allotment Authority Increase Proposal;

"FOR" the Ensco General Disapplication of Pre-emptive Rights Proposal; and

"FOR" the Ensco Specified Disapplication of Pre-emptive Rights Proposal.

Q:
How will my shares of Atwood common stock be voted?

A:
All shares of Atwood common stock entitled to vote and represented by properly completed proxies received prior to the Atwood special meeting, and not revoked, will be voted at the

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Q:
Can I revoke my proxy or voting instructions or change my vote after I have delivered my proxy or voting instructions?

A:
Yes. If you are a shareholder of record of Ensco Class A ordinary shares or Atwood common stock, you can do this in any of the three following ways:

by sending a written notice to the Secretary of Ensco or the Corporate Secretary of Atwood, as applicable, at the address set forth in the Ensco notice of general meeting or Atwood notice of special meeting, as applicable, in time to be received before such meeting, stating that you would like to revoke your proxy;

by completing, signing and dating another proxy card and returning it by mail in time to be received before the Ensco general meeting or the Atwood special meeting, as applicable, or by submitting a later dated proxy via the Internet or telephone, in which case your later-submitted proxy will be recorded and your earlier proxy revoked; or

by attending the meeting and voting in person (simply attending the Ensco general meeting or Atwood special meeting, as applicable, without voting will not revoke your proxy or change your vote).
Q:
What happens if I hold both Ensco Class A ordinary shares and shares of Atwood common stock?

A:
You will receive separate proxy or voting instruction cards for each company and must complete, sign and date each proxy or voting instruction card and return each proxy or voting instruction card in the appropriate postage-paid envelope or, if available, by submitting a proxy or voting instructions by telephone or through the Internet for each company.

Q:
What are the U.S. federal income tax consequences of the merger to Atwood shareholders?

A:
In general, subject to the discussion below relating to the potential application of Section 304 of the U.S. Internal Revenue Code of 1986, as amended (the "Internal Revenue Code") under the section of this joint proxy statement/prospectus entitled "Material United States Federal Income Tax Consequences of the Merger—Tax Consequences of the Merger to Atwood Shareholders," the receipt by U.S. holders (as defined in the section of this joint proxy statement/prospectus entitled "Material United States Federal Income Tax Consequences of the Merger") of Ensco Class A ordinary shares pursuant to the merger should be a taxable exchange for U.S. federal income tax purposes. Assuming such treatment, a U.S. holder generally will recognize capital gain or loss equal to the difference between (i) the fair market value of the Ensco Class A ordinary shares received as consideration in the merger on the date of the exchange and (ii) such U.S. holder's adjusted tax basis in the shares of Atwood common stock surrendered in the exchange. A U.S. holder's adjusted basis in its shares of Atwood common stock will generally equal such U.S.

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Q:
Who can answer my questions?

A:
If you have any questions about the merger or how to submit your proxy or voting instructions, or if you need additional copies of this joint proxy statement/prospectus, the enclosed proxy or voting instructions card, you should contact:
If you are an Ensco shareholder:   If you are an Atwood shareholder:

Proxy Solicitor:
D.F. King & Co., Inc.

 

Proxy Solicitor:
Innisfree M&A Incorporated

Shareholders Call Toll-Free at:
(888) 626-0988

 

Shareholders Call Toll-Free at:
(888) 750-5834

Banks and Brokers Call Collect at:
(212) 269-5550

 

Banks and Brokers Call Collect at:
(212) 750-5833

or

 

 

MacKenzie Partners, Inc.

 

 

Shareholders Call Toll-Free at:
(800) 322-2885

 

 

Banks and Brokers Call Collect at:
(212) 929-5500

 

 

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SUMMARY

        This summary highlights information contained elsewhere in this joint proxy statement/prospectus. Ensco and Atwood urge you to read carefully the remainder of this joint proxy statement/prospectus, including the attached annexes and the other documents to which we refer to herein and documents incorporated by reference into this joint proxy statement/prospectus, as this section does not provide all the information that might be important to you with respect to the merger and the other matters being considered at the Ensco general meeting or Atwood special meeting, as applicable. See also the section entitled "Where You Can Find More Information" beginning on page 178. We have included page references to direct you to a more complete description of the topics presented in this summary.

The Companies (See page 141)

Ensco plc

        Ensco is a global offshore contract drilling company and one of the leading providers of offshore contract drilling services to the international oil and gas industry. Ensco owns and operates an offshore drilling rig fleet of 53 rigs, with drilling operations in most of the strategic markets around the globe. Ensco also has two rigs under construction. For the three and six months ended June 30, 2017, Ensco's operating revenue totaled approximately $457.5 million and $928.6 million, respectively. For the year ended December 31, 2016, Ensco had annual revenue of approximately $2.8 billion and employed approximately 4,900 personnel.

        The Ensco Class A ordinary shares are listed on the NYSE under the symbol "ESV." Ensco is a public limited company organized under the laws of England and Wales. Ensco's principal executive offices are located at 6 Chesterfield Gardens, London, W1J 5BQ, United Kingdom and its telephone number is 44 (0) 20 7659 4660.

        Additional information about Ensco and its subsidiaries is included in documents incorporated by reference in this joint proxy statement/prospectus. See "Where You Can Find More Information" beginning on page 178.

Echo Merger Sub LLC

        Merger Sub, a wholly owned subsidiary of Ensco, is a Texas limited liability company formed on May 26, 2017 for the purpose of effecting the merger. Under the merger agreement, Merger Sub will merge with and into Atwood, with Atwood continuing as the surviving company and a wholly owned subsidiary of Ensco. Merger Sub has not conducted any activities other than those incidental to its formation and the matters contemplated by the merger agreement, including the preparation of applicable regulatory filings in connection with the merger.

Atwood Oceanics, Inc.

        Atwood is a global offshore drilling contractor engaged in the drilling and completion of exploratory and developmental oil and gas wells. Atwood currently owns a diversified fleet of 10 mobile offshore drilling units located in the Mediterranean Sea, offshore West Africa, offshore Southeast Asia and offshore Australia. Atwood recently executed a sale and recycling agreement with respect to one of the drilling units. For the three and nine months ended June 30, 2017, Atwood's operating revenue totaled $117 million and $442 million, respectively. For the year ended September 30, 2016, Atwood's operating revenues totaled $1.0 billion and Atwood employed 938 personnel.

        The Atwood common stock is listed on the NYSE under the symbol "ATW." Atwood's registered office and principal executive offices are located at 15011 Katy Freeway, Suite 800, Houston, Texas 77094 and its telephone number is (281) 749-7800.

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        Additional information about Atwood and its subsidiaries is included in documents incorporated by reference in this joint proxy statement/prospectus. See "Where You Can Find More Information" beginning on page 178.

The Merger (See page 49)

        The merger agreement provides that Merger Sub will merge with and into Atwood, with Atwood continuing as the surviving company and a wholly owned subsidiary of Ensco. The terms and conditions of the merger are contained in the merger agreement, which is attached as Annex A to this joint proxy statement/prospectus. Please carefully read the merger agreement as it is the legal document that governs the merger.

Merger Consideration (See page 99)

        Subject to the terms and conditions set forth in the merger agreement, at the effective time of the merger (the "Effective Time"), each share of Atwood common stock issued and outstanding immediately prior to the Effective Time will be converted into the right to receive 1.60 Ensco Class A ordinary shares. The merger agreement does not contain any provision that would adjust the exchange ratio based on the fluctuations in the market value of either the Atwood common stock or Ensco Class A ordinary shares. Because of this, the implied value of the merger consideration to the Atwood shareholders will fluctuate between now and the completion of the merger.

Comparative Market Prices and Share Information (See page 18)

        The Ensco Class A ordinary shares are quoted on the NYSE under the symbol "ESV," and the Atwood common stock is quoted on the NYSE under the symbol "ATW." The following table shows the closing sale prices of Ensco Class A ordinary shares and Atwood common stock as reported on the NYSE on May 26, 2017, the last trading day prior to the announcement of the merger, and on August 17, 2017, the last practicable trading day prior to the date of this joint proxy statement/prospectus.

 
  Price
per Ensco
Class A
Ordinary Shares
  Price per
Share of Atwood
Common Stock
  Equivalent per
Share Value
 

May 26, 2017

  $ 6.70   $ 8.08   $ 10.72  

August 17, 2017

  $ 4.16   $ 6.04   $ 6.66  

        The market price of the Ensco Class A ordinary shares and the Atwood common stock will fluctuate prior to the completion of the merger. You should obtain current stock price quotations for Ensco Class A ordinary shares and Atwood common stock.

Treatment of Atwood Equity-Based Awards (See page 100)

        Pursuant to the terms of the merger agreement, each award of Atwood restricted stock units other than any Atwood restricted stock units that are required to be settled in cash ("Atwood RSUs") that is outstanding as of immediately prior to the Effective Time shall vest upon the Effective Time. As soon as practicable after the Effective Time, the Atwood RSUs will be settled through the issuance to the holders thereof of Ensco Class A ordinary shares in an amount equal to the number of shares of Atwood common stock originally subject to such award multiplied by the exchange ratio (rounded down to the nearest whole share). Each award of Atwood restricted stock units that is required to be settled in cash ("Atwood Cash Units") will be treated in accordance with the terms of such award.

        Each award of Atwood stock options that remains outstanding and unexercised immediately prior to the Effective Time (an "Existing Option"), will, as of the Effective Time, automatically and without

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any further action being required, be converted into a stock option relating to the Ensco Class A ordinary shares, on the same terms and conditions (including the same expiration restrictions) as were applicable to such Existing Option immediately prior to the Effective Time (a "Converted Option"), except that (i) the number of Ensco Class A ordinary shares subject to the Converted Option will be determined by multiplying the number of shares of Atwood common stock subject to the corresponding Existing Option immediately prior to the Effective Time by the exchange ratio, and then rounded down to the nearest whole share, and (ii) the exercise price per share of the Converted Option will equal the per share exercise or strike price of the Existing Option immediately prior to the Effective Time divided by the exchange ratio, rounded up to the nearest whole cent.

Material U.S. Federal Income Tax Consequences (See page 130)

        In general, subject to the discussion relating to the potential application of Section 304 of the Internal Revenue Code under the section entitled "Material United States Federal Income Tax Consequences of the Merger—Tax Consequences of the Merger to Atwood Shareholders," the receipt by U.S. holders (as defined in the section of this joint proxy statement/prospectus entitled "Material United States Federal Income Tax Consequences of the Merger") of Ensco Class A ordinary shares pursuant to the merger should be a taxable exchange for U.S. federal income tax purposes. Assuming such treatment, a U.S. holder generally will recognize capital gain or loss equal to the difference between (i) the fair market value of the Ensco Class A ordinary shares received as consideration in the merger on the date of the exchange and (ii) the holder's adjusted tax basis in the shares of Atwood common stock surrendered in the exchange. A U.S. holder's adjusted basis in its shares of Atwood common stock generally will equal such holder's purchase price for such shares, as adjusted to take into account stock dividends, certain non-dividend distributions, stock splits and similar transactions. For further information, please refer to "Material United States Federal Income Tax Consequences of the Merger."

        A non-U.S. holder (as defined in the section of this joint proxy statement/prospectus entitled "Material United States Federal Income Tax Consequences of the Merger") generally should not be subject to U.S. federal income tax on any gain recognized in the merger other than in certain specific circumstances (including as a result of the potential application of Section 304 of the Internal Revenue Code), as further described under the section of this joint proxy statement/prospectus entitled "Material United States Federal Income Tax Consequences of the Merger—Tax Consequences of the Merger to Atwood Shareholders."

        The United States federal income tax consequences described above may not apply to all Atwood shareholders. Your tax consequences will depend on your individual situation. Accordingly, we strongly urge you to consult your tax advisor for a full understanding of the particular tax consequences of the merger to you.

Ensco General Meeting (See page 33)

        The Ensco general meeting will be held at the offices of Slaughter and May, One Bunhill Row, London EC1Y 8YY, England, at 3:00 P.M. (London time) on October 5, 2017.

        All Ensco shareholders of record at the close of business in London on August 23, 2017, the Ensco record date, are entitled to notice of, and to attend and vote at, the Ensco general meeting or, subject to the Ensco Articles of Association, any adjournments or postponements of the Ensco general meeting. This joint proxy statement/prospectus is being sent to Ensco shareholders beginning August 21, 2017.

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        At the Ensco general meeting, Ensco shareholders will be asked to approve, in addition to all subsisting authorities:

        As a U.K. company publicly traded on the NYSE, Ensco shareholder approval of the Ensco Merger Consideration Proposal is subject to the shareholder approval requirements under both the Companies Act 2006 and NYSE rules. The Ensco Merger Consideration Proposal is being proposed as an ordinary resolution. Assuming a quorum is present, such proposal will be approved for purposes of the Companies Act 2006 and NYSE rules if a majority of the votes cast are cast in favor thereof. The Ensco General Allotment Authority Increase Proposal will be proposed as an ordinary resolution and, assuming a quorum is present, will be approved if a majority of the votes cast are cast in favor thereof. Each of the Ensco General Disapplication of Pre-emptive Rights Proposal and the Ensco Specified Disapplication of Pre-emptive Rights Proposal will be proposed as a special resolution, which means, assuming a quorum is present, each such proposal will be approved if at least 75% of the votes cast are cast in favor thereof.

        Approval of the Ensco Merger Consideration Proposal is required for completion of the merger. Approval of the other Ensco proposals set forth above is not required in order to complete the merger.

        In connection with the Ensco general meeting, abstentions and broker non-votes will be considered in determining the presence of a quorum. While abstentions and broker non-votes are not considered votes cast under the Companies Act 2006, under NYSE rules abstentions, but not broker non-votes, will be considered as votes cast for determining whether a sufficient number of votes have been cast on a particular proposal. As a result, for purposes of determining whether the Ensco Merger Consideration Proposal has been approved in accordance with the Companies Act 2006, abstentions and broker non-votes will not have any effect on the outcome of the vote. With respect to NYSE rules, abstentions will have the same effect as votes cast "AGAINST" the Ensco Merger Consideration Proposal and broker non-votes will not have any effect on the outcome of the vote. Abstentions and broker non-votes will have no effect on the outcome of the Ensco General Allotment Authority Increase Proposal, the Ensco General Disapplication of Pre-emptive Rights Proposal or the Ensco Specified Disapplication of Pre-emptive Rights Proposal.

        As of August 17, 2017, directors and executive officers of Ensco and its affiliates had the right to vote approximately 1,903,037 Ensco Class A ordinary shares, or approximately 0.63% of the outstanding Ensco Class A ordinary shares on that date.

        After careful consideration, on May 29, 2017, the Ensco Board unanimously determined that the form, terms and provisions of the merger agreement and the transactions contemplated thereby, including the merger and the allotment and issuance of the Ensco Class A ordinary shares, are advisable, fair and reasonable to and in the best interests of Ensco and its shareholders. The Ensco Board unanimously recommends that Ensco shareholders vote "FOR" the Ensco Merger Consideration Proposal. For a more complete description of the recommendation of the Ensco Board with respect to the Ensco Merger Consideration Proposal, see "The Merger—Ensco's Reasons for the Merger; Recommendation of the Ensco Board of Directors" beginning on page 57.

        In addition, the Ensco Board recommends that Ensco shareholders vote "FOR" the Ensco General Allotment Authority Increase Proposal, "FOR" the Ensco General Disapplication of Pre-Emptive Rights Proposal and "FOR" the Ensco Specified Disapplication of Pre-Emptive Rights Proposal.

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Atwood Special Meeting (See page 45)

        The Atwood special meeting will be held at 15011 Katy Freeway, First Floor, Houston, Texas 77094, at 9:00 A.M. (Houston time) on October 5, 2017. Only Atwood shareholders of record at the close of business on August 23, 2017, the Atwood record date, are entitled to notice of, and to vote at, the Atwood special meeting and any adjournments or postponements of the Atwood special meeting.

        At the Atwood special meeting, Atwood shareholders will be asked to consider and approve:

        The Atwood Merger Proposal requires the approval of Atwood shareholders holding at least two-thirds of the Atwood common stock entitled to vote thereon pursuant to the requirements of the TBOC. Assuming a quorum is present, the Atwood Compensatory Proposal requires the approval of a majority of votes cast by the Atwood shareholders present, in person or by proxy, at the Atwood special meeting. Whether or not a quorum is present, the Atwood Adjournment Proposal requires the approval of a majority of votes cast by the Atwood shareholders present, in person or by proxy, at the Atwood special meeting.

        Approval of the Atwood Merger Proposal is required for completion of the merger. Approval of the other Atwood proposals set forth above is not required in order to complete the merger.

        In connection with the Atwood special meeting, abstentions and broker non-votes will be considered in determining the presence of a quorum. Abstentions and broker non-votes will have the same effect as votes cast "AGAINST" the Atwood Merger Proposal, but will have no effect on the outcome of the Atwood Compensatory Proposal or the Atwood Adjournment Proposal.

        As of August 17, 2017, directors and executive officers of Atwood and its affiliates, had the right to vote approximately 491,689 shares of Atwood common stock, or approximately 0.61% of the outstanding shares of Atwood common stock on that date.

        After careful consideration, on May 29, 2017, the Atwood Board unanimously determined that the merger agreement and the transactions contemplated by the merger agreement, including the merger, are advisable and in the best interests of Atwood and its shareholders. The Atwood Board unanimously recommends that Atwood shareholders vote "FOR" the Atwood Merger Proposal. For a more complete description of the recommendation of the Atwood Board with respect to the Atwood Merger Proposal, see "The Merger—Atwood's Reasons for the Merger; Recommendation of the Atwood Board of Directors" beginning on page 59.

        In addition, the Atwood Board recommends the Atwood shareholders vote "FOR" the Atwood Compensatory Proposal and "FOR" the Atwood Adjournment Proposal.

Opinion of Financial Advisor to Ensco (See page 63 and Annex B)

        On May 29, 2017, at a meeting of the Ensco Board, Morgan Stanley & Co. LLC ("Morgan Stanley") rendered its oral opinion to the Ensco Board, subsequently confirmed by delivery of a written opinion, dated May 29, 2017, that, as of that date, and based upon and subject to the various assumptions made, procedures followed, matters considered and qualifications and limitations on the scope of review undertaken as set forth in the written opinion, the exchange ratio pursuant to the merger agreement was fair from a financial point of view to Ensco.

        The full text of the written opinion of Morgan Stanley to the Ensco Board, dated as of May 29, 2017, is attached as Annex B to this joint proxy statement/prospectus and is incorporated herein by

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reference in its entirety. The summary of the opinion of Morgan Stanley in this joint proxy statement/prospectus is qualified in its entirety by reference to the full text of the opinion. You should read Morgan Stanley's opinion, this section and the summary of Morgan Stanley's opinion carefully and in their entirety for a discussion of the assumptions made, procedures followed, matters considered and qualifications and limitations upon the review undertaken by Morgan Stanley in rendering its opinion. Morgan Stanley's opinion was directed to the Ensco Board, in its capacity as such, and addressed only the fairness from a financial point of view to Ensco of the exchange ratio pursuant to the merger agreement as of the date of such opinion.

        Morgan Stanley's opinion did not address any other aspects or implications of the merger. Morgan Stanley's opinion did not in any manner address the price at which the Ensco Class A ordinary shares would trade following the merger or at any time, and Morgan Stanley expressed no opinion or recommendation to any holder of Ensco Class A ordinary shares or Atwood common stock as to how such holder should vote at the Ensco general meeting or the Atwood special meeting, respectively, or whether to take any other action with respect to the merger.

Opinion of Financial Advisor to Atwood (See page 75 and Annex C)

        Goldman Sachs & Co. LLC ("Goldman Sachs") delivered its opinion to the Atwood Board that, as of May 29, 2017 and based upon and subject to the factors and assumptions set forth therein, the exchange ratio pursuant to the merger agreement was fair from a financial point of view to the holders (other than Ensco and its affiliates) of shares of Atwood common stock.

        The full text of the written opinion of Goldman Sachs, dated May 29, 2017, which sets forth assumptions made, procedures followed, matters considered and limitations on the review undertaken in connection with the opinion, is attached as Annex C to this joint proxy statement/prospectus. Goldman Sachs provided its opinion for the information and assistance of the Atwood Board in connection with its consideration of the transaction. The Goldman Sachs opinion is not a recommendation as to how any holder of shares of Atwood common stock should vote with respect to the transaction or any other matter. Pursuant to an engagement letter between Atwood and Goldman Sachs, Atwood has agreed to pay Goldman Sachs a transaction fee that is estimated, based on the information available as of the date of announcement of the transaction, at approximately $21 million, $3 million of which became payable upon execution of the merger agreement, and the remainder of which is contingent upon consummation of the merger.

Interests of Atwood Directors and Executive Officers in the Merger (See page 93)

        Atwood's directors and executive officers have financial interests in the merger that may be different from, or in addition to, those of Atwood shareholders generally. The Atwood Board was aware of these interests and considered them, among other matters, in approving the merger agreement and making its recommendation that Atwood shareholders approve the Atwood Merger Proposal. These interests include the following:

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        Atwood's directors and executive officers are also entitled to continued indemnification/expense advancement and directors' and officers' liability insurance coverage under the merger agreement.

Board of Directors and Executive Officers of Ensco Following the Merger (See page 91)

        The current directors of Ensco are: Paul E. Rowsey, III, Carl Trowell, J. Roderick Clark, Roxanne J. Decyk, Mary E. Francis CBE, C. Christopher Gaut, Gerald W. Haddock, Francis S. Kalman and Keith O. Rattie. At the Effective Time, Ensco will cause two directors currently serving on the Atwood Board, Jack E. Golden and Phil D. Wedemeyer, to be appointed to the Ensco Board and will expand the Ensco Board to the extent necessary in connection with appointing such additional directors. The two additional directors were proposed by Atwood following the execution of the merger agreement and have been mutually agreed upon by Ensco and Atwood. All Ensco directors are elected annually to serve until the next annual meeting and until their successors are elected.

        Ensco's executive officers will remain the same following the merger, and none of Atwood's executive officers are expected to have any executive officer positions with the combined company.

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Public Trading Markets (See page 91)

        The Ensco Class A ordinary shares are quoted on the NYSE under the symbol "ESV," and the Atwood common stock is quoted on the NYSE under the symbol "ATW." Upon completion of the merger, the Atwood common stock will be delisted from the NYSE and deregistered under the Securities Exchange Act of 1934, as amended (the "Exchange Act"). The Ensco Class A ordinary shares issuable in the merger will be listed on the NYSE and will be freely transferable under the Securities Act of 1933, as amended (the "Securities Act").

Regulatory Approvals Required for the Merger (See page 92)

        To complete the merger, Ensco and Atwood must make filings with and obtain authorizations, approvals or consents from a number of regulatory authorities. The merger is subject to the requirements of the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended (the "HSR Act"). On June 9, 2017, Ensco and Atwood filed a Premerger Notification and Report Form pursuant to the HSR Act with the Antitrust Division of the Department of Justice (the "DOJ") and the Federal Trade Commission (the "FTC"). On June 27, 2017, the DOJ and the FTC granted early termination of the waiting period under the HSR Act. In addition, the new Ensco Class A ordinary shares to be issued to Atwood shareholders must be approved for listing on the NYSE, subject to official notice of issuance.

Expected Timing of the Merger (See page 99)

        Unless Ensco and Atwood agree otherwise, completion of the merger will occur as soon as practicable, but no later than within five business days after the satisfaction or waiver of the conditions set forth in the merger agreement, except for those conditions that are to be satisfied at the closing. The parties expect such conditions to be satisfied in the third calendar quarter of 2017. However, as the merger is subject to regulatory clearance and the satisfaction or waiver of other conditions described in the merger agreement, it is possible that factors outside the control of Ensco and Atwood could result in the merger being completed at a later time or not at all.

Adverse Recommendation Changes (See page 109)

        Subject to the conditions described in this joint proxy statement/prospectus, the merger agreement provides that neither the Ensco Board nor the Atwood Board will:

        The taking or failure to take, as applicable, of any of the actions described above is referred to as an "adverse recommendation change." Subject to the conditions described in this joint proxy statement/prospectus, prior to receiving shareholder approval of the Ensco Merger Consideration Proposal or the Atwood Merger Proposal, as applicable, either the Ensco Board or the Atwood Board

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may make an adverse recommendation change in response to an event (an "intervening event") that (i) was not known to such board of directors (or the material consequences of which, based on facts known to members of such board of directors as of the date of the merger agreement, were not reasonably foreseeable as of the date of the merger agreement); (ii) becomes known by such board of directors prior to the receipt of shareholder approval; and (iii) does not relate to the receipt, existence or terms of a takeover proposal involving Ensco or Atwood, as applicable. Either the Ensco Board or the Atwood Board may make an adverse recommendation change in response to an intervening event if such board of directors has determined in good faith after consultation with its outside financial advisors and outside legal counsel that the failure to take such action would be inconsistent with its fiduciary duties under applicable law, subject to certain conditions described in this joint proxy statement/prospectus.

Agreement Not to Solicit Other Offers (See page 109)

        Except as expressly permitted by the merger agreement, each party will, and will cause its affiliates, and officers, directors and employees to, and will use reasonable best efforts to cause its agents, financial advisors, investment bankers, attorneys, accountants and other representatives to:

        In addition, neither party will release any third party from or waive or amend any standstill provision or confidentiality provision other than any confidentiality provision the waiver of which would not be reasonably likely to lead to a takeover proposal, and each party will enforce such confidentiality and standstill provisions of any such agreements and take all steps within its power to terminate any waivers previously granted under any such provisions.

Conditions to Completion of the Merger (See page 114)

        Each party's obligation to consummate the merger is conditioned upon the satisfaction (or waiver by such party) at or prior to the completion of the merger of each of the following:

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Termination of the Merger Agreement (See page 114)

        Generally, the merger agreement may be terminated prior to the completion of the merger, whether before or after the Ensco Merger Consideration Proposal or the Atwood Merger Proposal is approved (as applicable and except as otherwise specified below), as follows:

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Termination Fees (See page 116)

        Atwood must pay Ensco a $30 million termination fee (the "Atwood Termination Fee") if:

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        Ensco must pay Atwood a $50 million termination fee (the "Ensco Termination Fee") if:

Expense Reimbursement (See page 116)

        If the merger agreement is terminated by either party due to the breach by the other party of its representations, warranties and covenants set forth in the merger agreement, then the breaching party will reimburse all reasonable out-of-pocket fees and expenses incurred by the other party in connection with the merger up to $10 million. In addition, Atwood will reimburse Ensco up to $10 million of all reasonable out-of-pocket fees and expenses incurred in connection with the merger in the event that Atwood does not obtain shareholder approval of the Atwood Merger Proposal.

Accounting Treatment of the Merger (See page 92)

        Ensco prepares its financial statements in accordance with generally accepted accounting principles in the United States ("GAAP"). The merger will be accounted for using the acquisition method of accounting with Ensco being considered the acquirer of Atwood for accounting purposes. This means that Ensco will allocate the purchase price to the fair value of Atwood's tangible and intangible assets and liabilities at the acquisition date, with the excess purchase price, if any, being recorded as goodwill, or the excess of the fair value of Atwood's tangible and intangible assets and liabilities at the acquisition date over the purchase price, if any, being recognized in Ensco's earnings. Under the acquisition method of accounting, goodwill is not amortized but is tested for impairment at least annually.

No Appraisal or Dissenters' Rights (See page 91)

        Atwood shareholders who dissent to the merger will not have rights to an appraisal of the fair value of their shares. Under the TBOC, shareholders generally have appraisal rights in the event of a merger or consolidation. However, these appraisal rights are not available if (i) the shares held by the shareholder are part of a class of shares listed on a national securities exchange or held of record by at least 2,000 holders, (ii) the shareholder is not required to accept for his or her shares any consideration that is different than the consideration to be provided to any other holder of shares of the same class held by the shareholder, and (iii) the shareholder is not required to accept any consideration other than shares of a corporation that satisfy the requirements in clause (i) above. Because Ensco Class A ordinary shares are listed on the NYSE, a national securities exchange, and are expected to continue to be so listed following the merger, and because the merger otherwise satisfies the foregoing requirements, Atwood shareholders will not be entitled to appraisal or dissenters' rights in the merger with respect to their shares of Atwood common stock.

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Comparison of Shareholder Rights (See page 148)

        Upon completion of the merger, Atwood shareholders will become Ensco shareholders and will have different rights once they become Ensco shareholders due to differences between the governing corporate documents of each entity. These differences are described in detail in the section entitled "Comparison of Rights of Atwood Shareholders and Ensco Shareholders" beginning on page 148.

Litigation Relating to the Merger (See page 92)

        On June 23, 2017, a putative class action lawsuit was filed against Atwood, Atwood's directors, Ensco and Merger Sub. The complaint generally alleges that the directors and Atwood disseminated a false or misleading registration statement which omitted material information regarding the proposed transaction between Ensco and Atwood, in violation of Section 14(a) of the Exchange Act. Specifically, the complaint alleges that Atwood and the directors omitted material information regarding the parties' financial projections, the analysis performed by Goldman Sachs in support of its fairness opinion, the timing and nature of communications regarding post-transaction employment of Atwood's directors and officers, potential conflicts of interest of Goldman Sachs, and whether there were further discussions with another potential acquirer of Atwood following announcement of the merger. The complaint seeks injunctive relief, including to enjoin the merger, rescission or rescissory damages in the event the merger is consummated, and an award of attorneys' fees, in addition to other relief. On June 27, June 29 and June 30, 2017, three additional putative class action lawsuits were filed against Atwood and Atwood's directors. These actions allege violations of Sections 14(a) and 20(a) of the Exchange Act by Atwood and Atwood's directors similar to those alleged in the original complaint discussed above; however, neither Ensco nor Merger Sub is named as a defendant in these actions.

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SELECTED HISTORICAL CONSOLIDATED FINANCIAL DATA OF ENSCO

        The following selected historical consolidated financial data for each of the years ended December 31, 2016, 2015, 2014, 2013 and 2012 are derived from Ensco's audited historical consolidated financial statements. Financial data for the six months ended June 30, 2017 and 2016 are derived from Ensco's unaudited consolidated financial statements. These historical results are not necessarily indicative of the future performance of Ensco following completion of the merger.

        You should read the following historical financial data in conjunction with "Management's Discussion and Analysis of Financial Condition and Results of Operations" and the consolidated financial statements and the related notes thereto set forth in Ensco's Annual Report on Form 10-K for the year ended December 31, 2016 and Form 10-Q for the quarterly period ended June 30, 2017, which are incorporated by reference into this joint proxy statement/prospectus. See "Where You Can Find More Information."

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  Year Ended December 31,   Six Months Ended
June 30,
 
(in millions, except per share amounts)
  2016   2015   2014   2013   2012   2017   2016  

Consolidated Statement of Operations Data

                                           

Revenues

  $ 2,776.4   $ 4,063.4   $ 4,564.5   $ 4,323.4   $ 3,638.8   $ 928.6   $ 1,723.6  

Operating expenses

                                           

Contract drilling (exclusive of depreciation)

    1,301.0     1,869.6     2,076.9     1,947.1     1,642.8     569.4     713.9  

Loss on impairment

        2,746.4     4,218.7                  

Depreciation

    445.3     572.5     537.9     496.2     443.8     217.1     225.7  

General and administrative

    100.8     118.4     131.9     146.8     148.9     56.5     50.8  

Operating income (loss)

    929.3     (1,243.5 )   (2,400.9 )   1,733.3     1,403.3     85.6     733.2  

Other income (expense), net

    68.2     (227.7 )   (147.9 )   (100.1 )   (98.6 )   (110.9 )   145.3  

Income tax expense (benefit)

    108.5     (13.9 )   140.5     203.1     228.6     43.4     108.1  

Income (loss) from continuing operations

    889.0     (1,457.3 )   (2,689.3 )   1,430.1     1,076.1     (68.7 )   770.4  

Income (loss) from discontinued operations, net

    8.1     (128.6 )   (1,199.2 )   (2.2 )   100.6     (.2 )   (1.1 )

Net income (loss)

    897.1     (1,585.9 )   (3,888.5 )   1,427.9     1,176.7     (68.9 )   769.3  

Net income attributable to noncontrolling interests

    (6.9 )   (8.9 )   (14.1 )   (9.7 )   (7.0 )   (2.3 )   (3.4 )

Net income (loss) attributable to Ensco

  $ 890.2   $ (1,594.8 ) $ (3,902.6 ) $ 1,418.2   $ 1,169.7   $ (71.2 ) $ 765.9  

Earnings (loss) per share—basic

                                           

Continuing operations

  $ 3.10   $ (6.33 ) $ (11.70 ) $ 6.09   $ 4.62   $ (0.24 ) $ 2.92  

Discontinued operations

    0.03     (0.55 )   (5.18 )   (0.01 )   0.43          

  $ 3.13   $ (6.88 ) $ (16.88 ) $ 6.08   $ 5.05   $ (0.24 ) $ 2.92  

Earnings (loss) per share—diluted

                                           

Continuing operations

  $ 3.10   $ (6.33 ) $ (11.70 ) $ 6.08   $ 4.61   $ (0.24 ) $ 2.92  

Discontinued operations

    0.03     (0.55 )   (5.18 )   (0.01 )   0.43          

  $ 3.13   $ (6.88 ) $ (16.88 ) $ 6.07   $ 5.04   $ (0.24 ) $ 2.92  

Net income (loss) attributable to Ensco shares—Basic and Diluted

  $ 873.6   $ (1,596.8 ) $ (3,910.5 ) $ 1,403.1   $ 1,157.4   $ (71.4 ) $ 753.9  

Weighted-average shares outstanding

                                           

Basic

    279.1     232.2     231.6     230.9     229.4     300.7     258.5  

Diluted

    279.1     232.2     231.6     231.1     229.7     300.7     258.5  

Cash dividends per share

  $ 0.04   $ 0.60   $ 3.00   $ 2.25   $ 1.50   $ 0.02   $ 0.02  

Consolidated Balance Sheet and Cash Flow Statement Data

                                           

Working capital

  $ 2,424.9   $ 1,509.6   $ 1,788.9   $ 466.9   $ 720.4   $ 2,028.8   $ 1,943.9  

Total assets

    14,374.5     13,610.5     16,023.3     19,446.8     18,554.7     13,723.9     13,765.0  

Long-term debt, net of current portion

    4,942.6     5,868.6     5,868.1     4,709.3     4,797.7     4,744.7     4,905.6  

Ensco shareholders' equity

    8,250.6     6,512.9     8,215.0     12,791.6     11,846.4     8,184.6     7,879.9  

Cash flows from operating activities of continuing operations

    1,077.4     1,697.9     2,057.9     1,811.2     1,954.6     130.5     800.2  

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SELECTED HISTORICAL CONSOLIDATED FINANCIAL DATA OF ATWOOD

        The following selected historical consolidated financial data for each of the fiscal years ended September 30, 2016, 2015, 2014, 2013 and 2012 are derived from Atwood's historical consolidated financial statements. Financial data for the nine months ended June 30, 2017 and 2016 are derived from Atwood's unaudited condensed consolidated financial statements also appearing herein and which, in the opinion of management, include all adjustments, consisting only of normal recurring adjustments, necessary for a fair statement of the results for the unaudited interim periods. These historical results are not necessarily indicative of the future performance of Atwood.

        You should read the following historical financial data in conjunction with "Management's Discussion and Analysis of Financial Condition and Results of Operations" and the consolidated financial statements and the related notes thereto set forth in Atwood's Annual Report on Form 10-K for the fiscal year ended September 30, 2016 and Quarterly Reports on Form 10-Q for the quarterly period ended June 30, 2017 and 2016, respectively, which are incorporated by reference into this joint proxy statement/prospectus. See "Where You Can Find More Information."

 
  At or For the Fiscal Years Ended September 30,   Nine Months Ended
June 30,
 
(In thousands, except per share amounts)
  2016   2015   2014   2013   2012   2017   2016  

Statement of Operations Data:

                                           

Total revenues

  $ 1,020,644   $ 1,395,851   $ 1,173,953   $ 1,063,663   $ 787,421   $ 442,496   $ 831,967  

Operating income (loss)

    294,282     531,430     438,784     429,471     319,410     25,468     280,512  

Net income (loss)

    265,272     432,573     340,822     350,224     272,171     (23,541 )   261,023  

Per Share Data:

                                           

Earnings (loss) per common share(1)

                                           

Basic

    4.09     6.70     5.31     5.38     4.17     (0.32 )   4.03  

Diluted

    4.09     6.65     5.24     5.32     4.14     (0.32 )   4.02  

Average common shares outstanding(1)

                                           

Basic

    64,789     64,581     64,240     65,073     65,267     74,515     64,750  

Diluted

    64,839     65,030     65,074     65,845     65,781     74,515     64,852  

Balance Sheet Data (as of end of period):

                                           

Total assets

    4,539,792     4,801,333     4,507,228     3,657,266     2,943,762     4,828,194     4,715,127  

Total debt

    1,227,919     1,678,268     1,742,122     1,263,232     830,000     1,298,136     1,374,780  

Total shareholder's equity

    3,230,386     2,947,170     2,555,524     2,207,371     1,939,422     3,399,822     3,222,520  

Statements of Cash Flow Data:

                                           

Net cash provided by operating activities

    625,008     604,287     442,620     432,110     255,603     248,828     515,415  

(1)
Potential dilutive Atwood common stock outstanding stock-based awards totaling 481,000 shares were considered in the calculation of diluted weighted-average shares for the nine months ended June 30, 2017; however, due to Atwood's net loss position, those shares have not been reflected above because they would be anti-dilutive.

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UNAUDITED COMPARATIVE PER SHARE DATA

        The following table sets forth (i) selected per share information for Ensco on a historical basis for the year ended December 31, 2016 and the six months ended June 30, 2017, (ii) selected per share information for Atwood on a historical basis for the year ended September 30, 2016 and the nine months ended June 30, 2017, (iii) unaudited selected per share information for Ensco on a pro forma basis after giving effect to the merger for the year ended December 31, 2016 and the six months ended June 30, 2017 and (iv) unaudited selected per share information for Atwood on an equivalent pro forma basis based on the exchange ratio of 1.60 Ensco Class A ordinary shares for each share of Atwood common stock for the year ended December 31, 2016 and the six months ended June 30, 2017.

        The pro forma information set forth below, while helpful in illustrating the financial characteristics of the combined company under one set of assumptions, does not reflect the possible impact on the combined company that may result as a consequence of the merger and, accordingly, does not attempt to predict or suggest future results. It also does not necessarily reflect what the historical results of the combined company would have been had our companies been combined during 2016. Upon completion of the merger, the operating results of Atwood will be reflected in the consolidated financial statements of Ensco on a prospective basis. You should read the data with the historical consolidated financial statements and related notes of Ensco and Atwood contained in their Annual Reports on Form 10-K for the years ended December 31, 2016 and September 30, 2016, respectively, and their respective Quarterly Reports on Form 10-Q for the quarter ended June 30, 2017, all of which are incorporated by reference into this joint proxy statement/prospectus. See "Where You Can Find More Information."

 
  Year Ended
December 31,
2016
  Six Months
Ended
June 30,
2017
 

Ensco—Historical

             

Book value per share

  $ 27.20   $ 26.93  

Cash dividends per share

    0.04     0.02  

Basic and diluted earnings per share

    3.10     (0.24 )

 

 
  Year Ended
September 30,
2016
  Nine Months
Ended
June 30,
2017
 

Atwood—Historical

             

Book value per share

  $ 49.85   $ 42.21  

Cash dividends per share

    0.075      

Basic and diluted earnings per share

    4.09     (0.32 )

 

 
  Year Ended
December 31,
2016
  Six Months
Ended
June 30,
2017
 

Ensco—Pro Forma Combined

             

Book value per share

  $ 21.43   $ 21.01  

Cash dividends per share

    0.115     0.02  

Basic and diluted earnings per share

    2.85     (0.02 )

 

 
  Year Ended
December 31,
2016
  Six Months
Ended
June 30,
2017
 

Equivalent Atwood

             

Book value per share

  $ 34.29   $ 33.62  

Cash dividends per share

    0.184     0.03  

Basic and diluted earnings per share

    4.56     (0.03 )

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COMPARATIVE MARKET PRICES AND DIVIDENDS

        Ensco Class A ordinary shares and Atwood common stock are listed on the NYSE. The following table sets forth the high and low sales prices of Ensco Class A ordinary shares and shares of Atwood common stock as reported on the NYSE, and the quarterly cash dividends declared per share for the periods indicated.

 
  Ensco Class A
Ordinary Shares
  Atwood Common Stock    
 
  High   Low   Dividend   High   Low   Dividend(2)    

Quarter Ended:

                                       

September 30, 2017 (through August 17, 2017)

  $ 5.80   $ 4.15     (1 ) $ 8.69   $ 6.00     N/A    

June 30, 2017

    9.34     4.89   $ 0.01     10.23     7.18        

March 31, 2017

    12.04     8.15   $ 0.01     14.39     8.44        

December 31, 2016

 
$

12.03
 
$

7.19
 
$

0.01
 
$

15.37
 
$

6.86
 
$

 

 

September 30, 2016

    10.89     6.50     0.01     13.79     6.12        

June 30, 2016

    12.36     9.00     0.01     13.33     7.52        

March 31, 2016

    16.10     7.25     0.01     11.46     4.82     0.075    

December 31, 2015

 
$

18.93
 
$

13.26
 
$

0.15
 
$

19.65
 
$

9.98
 
$

0.25
 

 

September 30, 2015

    22.21     13.46     0.15     26.50     14.15     0.25    

June 30, 2015

    28.40     21.04     0.15     35.66     25.89     0.25    

March 31, 2015

    32.28     19.78     0.15     35.24     26.12     0.25    

(1)
Dividends in respect of Ensco's quarter ending September 30, 2017 have not been declared or paid.

(2)
In March 2016, Atwood entered into an amendment to its revolving credit facility that, among other things, prohibits Atwood from paying dividends during the remaining term of its revolving credit facility.

        On May 26, 2017, the last full trading day before the public announcement of the merger agreement, the high and low sales prices of Ensco Class A ordinary shares as reported on the NYSE were $6.84 and $6.68, respectively. On August 17, 2017, the last full trading day before the date of this joint proxy statement/prospectus, the high and low sale prices of Ensco Class A ordinary shares as reported on the NYSE were $4.34 and $4.15, respectively.

        On May 26, 2017, the last full trading day before the public announcement of the merger agreement, the high and low sales prices of shares of Atwood common stock as reported on NYSE were $8.23 and $7.92, respectively. On August 17, 2017, the last full trading day before the date of this joint proxy statement/prospectus, the high and low sale prices of shares of Atwood common stock as reported on the NYSE were $6.37 and $6.00, respectively.

        Ensco shareholders and Atwood shareholders are advised to obtain current market quotations for Ensco Class A ordinary shares and Atwood common stock. The market price of Ensco Class A ordinary shares and Atwood common stock will fluctuate between the date of this joint proxy statement/prospectus and the completion of the merger. No assurance can be given concerning the market price of Ensco Class A ordinary shares or Atwood common stock before or after the Effective Time.

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RISK FACTORS

        In addition to the other information included or incorporated by reference in this joint proxy statement/prospectus, including the matters addressed in "Cautionary Statement Regarding Forward-Looking Statements" beginning on page 30, you should carefully consider the following risks before deciding how to vote. In addition, you should read and carefully consider the risks associated with each of Ensco and Atwood and their respective businesses. These risks can be found in Ensco's and Atwood's Annual Reports on Form 10-K for the year ended December 31, 2016 and September 30, 2016, respectively, and subsequent Quarterly Reports on Form 10-Q, each of which is filed with the SEC and incorporated by reference into this joint proxy statement/prospectus. For further information regarding the documents incorporated into this joint proxy statement/prospectus by reference, please see the section titled "Where You Can Find More Information." Realization of any of the risks described below, any of the events described under "Cautionary Statement Regarding Forward-Looking Statements" or any of the risks or events described in the documents incorporated by reference could have a material adverse effect on Ensco's, Atwood's or the combined company's businesses, financial condition, cash flows and results of operations and could result in a decline in the trading prices of Ensco's or Atwood's stock.

Risks Relating to the Merger

Because the exchange ratio will not be adjusted for stock price changes and the market price of Ensco Class A ordinary shares will fluctuate, Atwood shareholders cannot be sure of the value of the merger consideration they will receive.

        Upon completion of the merger, each share of Atwood common stock will be converted into the right to receive 1.60 Ensco Class A ordinary shares. The exchange ratio will not change to reflect changes in the market prices of the Ensco Class A ordinary shares and Atwood common stock. The market price of Ensco Class A ordinary shares at the time of completion of the merger may vary significantly from the market price of Ensco Class A ordinary shares on the date the merger agreement was executed, the date of this joint proxy statement/prospectus and the date of the Atwood special meeting. Accordingly, Atwood shareholders will not know or be able to calculate at the time of the Atwood special meeting the market value of the merger consideration they will receive upon completion of the merger.

        In addition, the merger might not be completed until a significant period of time has passed after the Atwood special meeting. Because the exchange ratio will not be adjusted to reflect any changes in the market values of Ensco Class A ordinary shares and Atwood common stock, the market value of the Ensco Class A ordinary shares issued, and the Atwood common stock surrendered, may be higher or lower than the values of those shares on earlier dates. Stock price changes may result from, among other things, changes in the business, operations or prospects of Ensco or Atwood prior to or following the merger, litigation or regulatory considerations, general business, market, industry or economic conditions and other factors both within and beyond the control of Ensco and Atwood. Neither Ensco nor Atwood is permitted to terminate the merger agreement solely because of changes in the market price of either company's stock.

The fairness opinions rendered by Ensco's and Atwood's financial advisors were based on the financial advisors' financial analysis and considered factors such as market and other conditions then in effect, and financial forecasts and other information made available to the financial advisors, as of the date of the opinions.

        The fairness opinions rendered to the Ensco Board and the Atwood Board by Morgan Stanley and Goldman Sachs, respectively, were provided in connection with, and at the time of, the evaluation of the merger and the merger agreement by the Ensco Board and the Atwood Board. The opinions were based on the financial, economic, market and other conditions as in effect on, and the information

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made available to, the financial advisors as of the date of the opinions. Events occurring after the date of such opinions may affect such opinions and the assumptions used in preparing them. Neither the Ensco Board nor the Atwood Board have obtained an updated opinion as of the date of this joint proxy statement/prospectus from their respective financial advisors, and neither the Ensco Board nor the Atwood Board expects to obtain an updated opinion prior to completion of the merger. Neither Morgan Stanley nor Goldman Sachs assumed any obligation to update, revise or reaffirm their respective opinions. Changes in the operations and prospects of Ensco or Atwood, general market and economic conditions and other factors that may be beyond the control of Ensco and Atwood, and on which the fairness opinions were based, may have altered the value of Ensco or Atwood or the prices of Ensco Class A ordinary shares or Atwood common stock since the date of such opinion, or may alter such values and prices by the time the merger is completed. The opinions do not speak as of any date other than the date of such opinion. For a description of the opinion that Morgan Stanley rendered to the Ensco Board, please refer to "The Merger—Opinion of Financial Advisor to Ensco." For a description of the opinion that Goldman Sachs rendered to the Atwood Board, please refer to "The Merger—Opinion of Financial Advisor to Atwood."

Current Atwood shareholders will have a reduced ownership and voting interest after the merger and will exercise less influence over management.

        Ensco will issue new Ensco Class A ordinary shares to Atwood shareholders in the merger (including Ensco Class A ordinary shares to be issued in connection with the vesting of certain outstanding Atwood equity awards). After giving effect to these issuances, current Ensco and Atwood shareholders are expected to hold approximately 69% and 31%, respectively, of the outstanding Ensco Class A ordinary shares immediately following completion of the merger.

        Atwood shareholders currently have the right to vote for their directors and on other matters affecting the company. When the merger occurs, the Ensco Class A ordinary shares that each Atwood shareholder receives in exchange for its Atwood common stock will represent a percentage ownership of Ensco that is significantly smaller than the Atwood shareholder's percentage ownership of Atwood. As a result of these reduced ownership percentages, former Atwood shareholders will have less influence on the management and policies of Ensco than they now have with respect to Atwood.

The merger agreement contains provisions that limit Ensco's and Atwood's ability to pursue alternatives to the merger, which could discourage a potential acquirer of Ensco or Atwood from making an alternative transaction proposal and, in certain circumstances, could require Ensco or Atwood to pay the other party a termination fee.

        Under the merger agreement, each of Ensco and Atwood is restricted from entering into alternative transactions. Unless and until the merger agreement is terminated, subject to specified exceptions (which are discussed in more detail in "The Merger Agreement"), each of Ensco, Atwood and their respective subsidiaries and representatives are prohibited from, directly or indirectly, initiating, soliciting, knowingly facilitating or knowingly encouraging (including by way of furnishing non-public information) any inquiry in respect of, or the making of any proposal or offer that constitutes or could reasonably be expected to lead to, a takeover proposal; engaging in, continuing or otherwise participating in any discussions or negotiations regarding, or furnishing to any other person any non-public information in connection with or for the purpose of encouraging or facilitating, a takeover proposal; or approving, recommending, or entering into any letter of intent or similar document, agreement, commitment or agreement in principle with respect to a takeover proposal. Under the merger agreement, in the event of a potential change by the Ensco Board of its recommendation with respect to the Ensco Merger Consideration Proposal or the Atwood Board of its recommendation with respect to the Atwood Merger Proposal, Ensco or Atwood, as the case may be, must provide the other party with at least four business days' prior written notice of its intention to

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take such action. In addition, each party is generally required to negotiate in good faith with the other party to modify the terms of the merger in response to any competing acquisition proposals before the party's board of directors, as the case may be, may change, qualify, withhold, withdraw or modify its recommendation with respect to the merger.

        If the merger agreement is terminated under specified circumstances, then Ensco or Atwood, as applicable, will be required to pay the other party's reasonable out-of-pocket fees and expenses up to a maximum amount of $10.0 million. In addition, if the merger agreement is terminated under specified circumstances, Ensco or Atwood will be required to pay the other party a termination fee of $50.0 million (in the case of a termination fee paid by Ensco) or $30.0 million (in the case of a termination fee paid by Atwood), in each case less any expense reimbursement previously paid by Ensco or Atwood. Following payment of a termination fee, neither party will be obligated to pay any additional expenses incurred by the other party or its affiliates. Please read "The Merger Agreement."

        These provisions could discourage a potential third-party acquirer that might have an interest in acquiring all or a significant portion of Ensco's or Atwood's stock or assets from considering or proposing that acquisition, even if it were prepared to pay consideration with a higher per share cash or market value than the market value proposed to be received or realized in the merger. Similarly, these provisions might result in a potential third-party acquirer proposing to pay a lower price to Atwood shareholders than it might otherwise have proposed to pay because of the added expense of the termination fee that may become payable in certain circumstances. If the merger agreement is terminated and Ensco or Atwood determines to seek another business combination, it may not be able to negotiate a transaction with another party on terms comparable to, or better than, the terms of the merger.

Ensco and Atwood will be subject to various uncertainties and contractual restrictions while the merger is pending that could adversely affect each party's business and operations.

        In connection with the merger, it is possible that some customers, suppliers and other persons with whom Ensco or Atwood has business relationships may delay or defer certain business decisions, or might decide to seek to terminate, change or renegotiate their relationship with Ensco or Atwood as a result of the merger, which could negatively affect Ensco's and Atwood's respective revenues, earnings and cash available for distribution, as well as the market price of Ensco Class A ordinary shares and Atwood common stock, regardless of whether the merger is completed.

        Under the terms of the merger agreement, each of Ensco and Atwood is subject to certain restrictions on the conduct of its business prior to completing the merger, which may adversely affect its ability to execute certain of its business strategies. Such limitations could negatively affect each party's businesses and operations prior to the completion of the merger. Furthermore, the process of planning to integrate two businesses and organizations for the post-merger period may divert management's attention and resources and could ultimately have an adverse effect on each party. These uncertainties could cause customers, suppliers and others that deal with Ensco or Atwood to seek to change existing business relationships with such party. For a discussion of these restrictions, see "The Merger Agreement—Covenants and Agreements."

Ensco or Atwood may have difficulty attracting, motivating and retaining executives and other employees in light of the merger.

        Uncertainty about the effect of the merger on Ensco or Atwood employees may impair these companies' ability to attract, retain and motivate personnel until the merger is completed. Employee retention may be particularly challenging during the pendency of the merger, as employees may feel uncertain about their future roles with the combined organization. In addition, Ensco or Atwood may have to provide additional compensation in order to retain employees. If employees of Ensco or

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Atwood depart because of issues relating to the uncertainty and difficulty of integration or a desire not to become employees of the combined company, the combined company's ability to realize the anticipated benefits of the merger could be adversely affected.

The merger is subject to conditions, including certain conditions that may not be satisfied, and may not be completed on a timely basis, if at all. Failure to complete the merger, or significant delays in completing the merger, could negatively affect the trading prices of Ensco Class A ordinary shares and Atwood common stock and the future business and financial results of Ensco and Atwood.

        The completion of the merger is subject to a number of conditions beyond Ensco's and Atwood's control that may prevent, delay or otherwise materially adversely affect its completion, including the approval by Ensco's shareholders of the Ensco Merger Consideration Proposal and the approval by Atwood's shareholders of the Atwood Merger Proposal. Neither Ensco nor Atwood can predict whether and when these other conditions will be satisfied. Any delay in completing the merger could cause the combined company not to realize some or all of the synergies expected to be achieved if the merger is successfully completed within its expected time frame. See "The Merger Agreement—Conditions to Complete the Merger."

        If the merger is not completed, each of Ensco and Atwood will be subject to several risks and consequences, including the following:

Ensco and Atwood will incur substantial transaction fees and costs in connection with the merger.

        Ensco and Atwood expect to incur a number of non-recurring transaction-related costs associated with completing the merger, combining the operations of the two organizations and achieving desired synergies. These fees and costs will be substantial. Non-recurring transaction costs include, but are not limited to, fees paid to legal, financial and accounting advisors, filing fees and printing costs. Additional unanticipated costs may be incurred in the integration of the businesses of Ensco and Atwood. There can be no assurance that the elimination of certain duplicative costs, as well as the realization of other efficiencies related to the integration of the two businesses, will offset the incremental transaction-related costs over time. Thus, any net benefit may not be achieved in the near term, the long term or at all.

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Certain directors and executive officers of Atwood have interests in the merger that are different from, or in addition to, those of other Atwood shareholders, which could have influenced their decisions to support or approve the merger.

        In considering whether to approve the proposals at the Atwood special meeting, Atwood shareholders should recognize that certain directors and executive officers of Atwood have interests in the merger that differ from, or that are in addition to, their interests as shareholders of Atwood. These interests include, among others, ownership interests in the combined company and the accelerated vesting of certain equity awards and/or certain severance benefits, in connection with the merger. These interests, among others, may influence the directors and executive officers of Atwood to support or approve the Atwood Merger Proposal. Please read "The Atwood Special Meeting—Proposal 2—Compensatory Proposal" and "The Merger—Atwood's Directors and Officers Have Financial Interests in the Merger."

Completion of the merger will trigger change of control or other provisions in certain agreements to which Atwood is a party.

        The completion of the merger will trigger change of control or other provisions in certain agreements to which Atwood is a party. In particular, the indenture governing Atwood's 6.50% senior notes due 2020 requires Atwood to make an offer to purchase all of each holder's notes at an amount equal to 101% of the aggregate principal amount of such holder's notes, plus accrued and unpaid interest, if any, within 30 days following a change of control. As a result, Ensco could be required to repay up to an aggregate $449 million principal amount of senior notes plus approximately $4.5 million in associated premiums.

        In addition, the completion of the merger will constitute a change of control under Atwood's revolving credit facility. As a result, the outstanding balance under the revolving credit facility will be accelerated and become due and payable by Ensco in connection with the completion of the merger. As of June 30, 2017, Atwood had outstanding borrowings under its revolving credit facility of approximately $850 million.

If a governmental authority asserts objections to the merger, Ensco and Atwood may be unable to complete the merger or, in order to do so, Ensco and Atwood may be required to comply with material restrictions or satisfy material conditions.

        The completion of the merger is subject to the condition that there is no law, injunction, judgment or ruling by a governmental authority in effect enjoining, restraining, preventing or prohibiting the merger contemplated by the merger agreement. If a governmental authority asserts objections to the merger, Ensco or Atwood may be required to divest assets or accept other remedies in order to complete the merger. There can be no assurance as to the cost, scope or impact of the actions that may be required to address any governmental authority objections to the merger. If Ensco or Atwood takes such actions, it could be detrimental to it or to the combined company following the consummation of the merger. Furthermore, these actions could have the effect of delaying or preventing completion of the merger or imposing additional costs on or limiting the revenues or cash available for distribution of the combined company following the consummation of the merger.

        Additionally, state attorneys general could seek to block or challenge the merger as they deem necessary or desirable in the public interest at any time, including after completion of the transaction. In addition, in some circumstances, a third party could initiate a private action under antitrust laws challenging or seeking to enjoin the merger, before or after it is completed. Ensco or Atwood may not prevail and may incur significant costs in defending or settling any action under the antitrust laws.

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Risks Relating to the Combined Company Following the Merger

If completed, the merger may not achieve its intended results, and Ensco and Atwood may be unable to successfully integrate their operations. Failure to successfully combine the businesses of Ensco and Atwood in the expected time frame may adversely affect the future results of the combined organization, and, consequently, the value of the Ensco Class A ordinary shares that Atwood shareholders receive as the merger consideration.

        Ensco and Atwood entered into the merger agreement with the expectation that the merger will result in various benefits, including, among other things, expanding Ensco's asset base and creating synergies. Achieving the anticipated benefits of the merger is subject to a number of uncertainties, including whether the businesses of Ensco and Atwood can be integrated in an efficient and effective manner.

        It is possible that the integration process could take longer than anticipated and could result in the loss of valuable employees, the disruption of each company's ongoing businesses, processes and systems or inconsistencies in standards, controls, procedures, practices, policies and compensation arrangements, any of which could adversely affect the combined company's ability to achieve the anticipated benefits of the merger. The combined company's results of operations could also be adversely affected by any issues attributable to either company's operations that arise or are based on events or actions that occur prior to the completion of the merger. The companies may have difficulty addressing possible differences in corporate cultures and management philosophies. The integration process is subject to a number of uncertainties, and no assurance can be given that the anticipated benefits will be realized or, if realized, the timing of their realization. Failure to achieve these anticipated benefits could result in increased costs or decreases in the amount of expected revenues and could adversely affect the combined company's future business, financial condition, operating results and prospects.

The pro forma financial statements included in this joint proxy statement/prospectus are based on various assumptions that may not prove to be correct, and they are presented for illustrative purposes only and may not be an indication of the combined company's financial condition or results of operations following the merger.

        The pro forma financial statements contained in this joint proxy statement/prospectus are based on various adjustments, assumptions and preliminary estimates and may not be an indication of the combined company's financial condition or results of operations following the merger for several reasons. See "Unaudited Pro Forma Condensed Combined Financial Statements of Ensco." The actual financial condition and results of operations of the combined company following the merger may not be consistent with, or evident from, these pro forma financial statements. In addition, the assumptions used in preparing the pro forma financial information may not prove to be accurate, and other factors may affect the combined company's financial condition or results of operations following the merger. Any potential decline in the combined company's financial condition or results of operations may cause significant variations in the price of Ensco Class A ordinary shares.

A downgrade in Ensco's or its subsidiaries' credit ratings following the merger could impact the combined entity's access to capital and costs of doing business, and maintaining credit ratings is under the control of independent third parties.

        Following the merger, rating agencies may reevaluate Ensco's and its subsidiaries' ratings, and any additional actual or anticipated downgrades in such credit ratings could limit their ability to access credit and capital markets, or to restructure or refinance their indebtedness. As a result of any such downgrades, future financings or refinancings may result in higher borrowing costs and require more restrictive terms and covenants, including obligations to post collateral with third parties, which may further restrict operations and negatively impact liquidity.

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        Credit rating agencies perform independent analysis when assigning credit ratings. The analysis includes a number of criteria including, but not limited to, business composition, market and operational risks, as well as various financial tests. Credit rating agencies continue to review the criteria for industry sectors and various debt ratings and may make changes to those criteria from time to time. Credit ratings are not recommendations to buy, sell or hold investments in the rated entity. Ratings are subject to revision or withdrawal at any time by the rating agencies, and Ensco cannot assure you that it will maintain its current credit ratings.

Ensco Class A ordinary shares to be received by Atwood shareholders as a result of the merger have different rights from Atwood common stock.

        Following completion of the merger, Atwood shareholders will no longer hold Atwood common stock, but will instead be Class A ordinary shareholders of Ensco. There are important differences between the rights of Atwood shareholders and the rights of Ensco Class A ordinary shareholders. See "Comparison of Rights of Atwood Shareholders and Ensco Shareholders" for a discussion of the different rights associated with Ensco Class A ordinary shares and Atwood common stock.

The IRS may not agree with the conclusion that Ensco should be treated as a foreign corporation for U.S. federal tax purposes following the merger.

        Although Ensco is incorporated in the United Kingdom, the U.S. Internal Revenue Service ("IRS") may assert that Ensco should be treated as a U.S. corporation (and, therefore, a U.S. tax resident) for U.S. federal income tax purposes following the merger pursuant to Section 7874 of the Internal Revenue Code. For U.S. federal income tax purposes, a corporation is generally considered a U.S. "domestic" corporation (or U.S. tax resident) if it is organized in the United States, and a corporation is generally considered a "foreign" corporation (or non-U.S. tax resident) if it is not a U.S. domestic corporation. Because Ensco is an entity incorporated in England and Wales, it would generally be classified as a foreign corporation (or non-U.S. tax resident) under these rules. Section 7874 of the Internal Revenue Code provides an exception under which a foreign incorporated entity may, in certain circumstances, be treated as a U.S. domestic corporation for U.S. federal income tax purposes.

        Unless Ensco satisfies the substantial business activities exception, as defined in Section 7874 of the Internal Revenue Code and described in more detail below (the "Substantial Business Activities Exception"), Ensco would be treated as a U.S. domestic corporation (that is, as a U.S. tax resident) for U.S. federal income tax purposes following the merger pursuant to Section 7874 of the Internal Revenue Code if the percentage (by vote or value) of Ensco Class A ordinary shares considered to be held by former holders of shares of Atwood common stock after the merger by reason of holding shares of Atwood common stock for purposes of Section 7874 of the Internal Revenue Code (the "Section 7874 Percentage") is 80% or more. In order for Ensco to satisfy the Substantial Business Activities Exception, at least 25% of the employees (by headcount and compensation), real and tangible assets and gross income of the Ensco expanded affiliated group must be based, located and derived, respectively, in the country in which Ensco is a tax resident after the merger. The Substantial Business Activities Exception is not expected to be satisfied.

        The Section 7874 Percentage is currently expected to be less than 60%. The calculation of the Section 7874 Percentage, however, is complex, is calculated based on the facts as of the Effective Time, is subject to detailed regulations (the application of which is uncertain in various respects and would be impacted by changes in such regulations) and is subject to factual uncertainties (including fluctuations in the value of shares of Atwood common stock and Ensco Class A ordinary shares). As a result, the IRS could assert that the Section 7874 Percentage is greater than 80% and that Ensco therefore is treated for U.S. federal income tax purposes as a U.S. domestic corporation (that is, as a U.S. tax resident) following the merger. If the IRS successfully challenged Ensco's status as a foreign

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corporation, significant adverse tax consequences would result for Ensco and for certain of Ensco's shareholders.

        Please see the section of this joint proxy statement/prospectus entitled "Material United States Federal Income Tax Consequences of the Merger—Tax Consequences of the Merger to Atwood and Ensco" for a discussion of the application of Section 7874 of the Internal Revenue Code to the merger.

It is uncertain whether Section 7874 of the Internal Revenue Code will impose an excise tax on gain recognized by certain individuals

        If the Section 7874 Percentage is calculated to be at least 60%, Section 7874 of the Internal Revenue Code and the rules related thereto may impose an excise tax under Section 4985 of the Internal Revenue Code (the "Section 4985 Excise Tax") on the gain recognized by certain "disqualified individuals" (including officers and directors of a U.S. company) on certain stock-based compensation held by them at a rate equal to 15%.

        Based on the guidance available, after taking into account the adjustments described in the section of this joint proxy statement/prospectus entitled "Material United States Federal Income Tax Consequences of the Merger—Tax Consequences of the Merger to Atwood and Ensco," and based on the facts and circumstances as of the date hereof, the Section 7874 Percentage following the merger is expected to be less than 60% and, thus, the Section 4985 Excise Tax is not expected to apply to "disqualified individuals" of Atwood or Ensco.

Future changes to U.S. and foreign tax laws could adversely affect Ensco.

        The U.S. Congress, the Organisation for Economic Co-operation and Development, and other government agencies in jurisdictions where Ensco and its affiliates do business have had an extended focus on issues related to the taxation of multinational corporations. One example is in the area of "base erosion and profit shifting," where payments are made between affiliates from a jurisdiction with high tax rates to a jurisdiction with lower tax rates. Additionally, recent legislative proposals would treat Ensco as a U.S. corporation if the management and control of Ensco and its affiliates were determined to be located primarily in the United States and/or would reduce the Section 7874 Percentage threshold at or above which Ensco would be treated as a U.S. corporation. Thus, the tax laws in the United States, the United Kingdom and other countries in which Ensco and its affiliates do business could change on a prospective or retroactive basis, and any such changes could adversely affect Ensco. Furthermore, the interpretation and application of domestic or international tax laws made by Ensco and Ensco's subsidiaries could differ from that of the relevant governmental authority, which could result in administrative or judicial procedures, actions or sanctions, which could be material.

U.S. tax laws and IRS guidance could affect Ensco's ability to engage in certain acquisition strategies and certain internal restructurings.

        Even if Ensco is treated as a foreign corporation for U.S. federal income tax purposes, Section 7874 of the Internal Revenue Code and U.S. Treasury Regulations promulgated thereunder, including temporary Treasury Regulations, may adversely affect the ability of Ensco to engage in certain future acquisitions of U.S. businesses in exchange for Ensco equity, which may affect the tax efficiencies that otherwise might be achieved in such potential future transactions.

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Risks Inherent in an Investment in Ensco

Transfers of Ensco Class A ordinary shares may be subject to stamp duty or stamp duty reserve tax ("SDRT") in the United Kingdom, which would increase the cost of dealing in Ensco Class A ordinary shares.

        Stamp duty and/or SDRT are imposed in the United Kingdom on certain transfers of chargeable securities (which include shares in companies incorporated in the United Kingdom) at a rate of 0.5% of the consideration paid for the transfer. Certain transfers of shares to depositary receipt facilities or clearance systems providers are charged at a higher rate of 1.5%.

        Pursuant to arrangements that Ensco entered into with the Depository Trust Company ("DTC"), the Ensco Class A ordinary shares are eligible to be held in book-entry form through the facilities of DTC. Transfers of shares held in book-entry form through DTC will not attract a charge to stamp duty or SDRT in the United Kingdom. A transfer of the shares from within the DTC system out of DTC and any subsequent transfers that occur entirely outside the DTC system will attract a charge to stamp duty at a rate of 0.5% of any consideration, which is payable by the transferee of the shares. Any such duty must be paid (and the relevant transfer document stamped by Her Majesty's Revenue & Customs ("HMRC")) before the transfer can be registered in the share register of Ensco. If a shareholder decides to redeposit shares into DTC, the redeposit will attract SDRT at a rate of 1.5% of the value of the shares.

        Ensco has put in place arrangements with its transfer agent to require that shares held in certificated form cannot be transferred into the DTC system until the transferor of the shares has first delivered the shares to a depository specified by Ensco so that SDRT may be collected in connection with the initial delivery to the depository. Any such shares will be evidenced by a receipt issued by the depository. Before the transfer can be registered in Ensco's share register, the transferor will also be required to provide the transfer agent sufficient funds to settle the resultant liability for SDRT, which will be charged at a rate of 1.5% of the value of the shares.

        Following decisions of the European Court of Justice and the U.K. First-tier Tax Tribunal, HMRC has announced that it will not seek to apply a charge to stamp duty or SDRT on the issuance of shares (or, where it is integral to the raising of new capital, the transfer of new shares) into a depositary receipt facility or clearance system provider, such as DTC. However, it is possible that the U.K. government may change or enact laws applicable to stamp duty or SDRT in response to this decision, which could have a material effect on the cost of trading in Ensco's shares.

If the Ensco Class A ordinary shares are not eligible for continued deposit and clearing within the facilities of DTC, then transactions in Ensco's shares may be disrupted.

        The facilities of DTC are widely-used for rapid electronic transfers of securities between participants within the DTC system, which include numerous major international financial institutions and brokerage firms. Currently, all trades of Ensco Class A ordinary shares on the NYSE are cleared and settled on the facilities of DTC. The Ensco Class A ordinary shares are, at present, eligible for deposit and clearing within the DTC system, pursuant to arrangements with DTC whereby DTC accepted the Ensco Class A ordinary shares for deposit, clearing and settlement services, and Ensco agreed to indemnify DTC for any stamp duty and/or SDRT that may be assessed upon it as a result of its service as a clearance system provider for the Ensco Class A ordinary shares. However, DTC retains sole discretion to cease to act as a clearance system provider for the Ensco Class A ordinary shares at any time.

        If DTC determines at any time that the Ensco Class A ordinary shares are no longer eligible for deposit, clearing and settlement services within its facilities, such shares may become ineligible for continued listing on a U.S. securities exchange, and trading in such shares would be disrupted. In this

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event, DTC has agreed it will provide Ensco advance notice and assist Ensco, to the extent possible, with efforts to mitigate adverse consequences. While Ensco would pursue alternative arrangements to preserve its listing and maintain trading, any such disruption could have a material adverse effect on the trading price of the Ensco Class A ordinary shares.

Investor enforcement of civil judgments against Ensco may be more difficult.

        Because Ensco is a public limited company incorporated under the Laws of England and Wales, investors could experience more difficulty enforcing judgments obtained against Ensco in U.S. courts. In addition, it may be more difficult (or impossible) to bring some types of claims against Ensco in courts in England than it would be to bring similar claims against a U.S. company in a U.S. court.

Ensco has less flexibility as a U.K. public limited company with respect to certain aspects of capital management than U.S. corporations due to increased shareholder approval requirements.

        Directors of Texas and other U.S. corporations may issue, without further shareholder approval, shares of common stock authorized in their certificates of incorporation that were not already issued or reserved. The business corporation laws of Texas and other U.S. states also provide substantial flexibility in establishing the terms of preferred stock. However, English law provides that a board of directors may only allot shares with the prior authorization of an ordinary resolution of the shareholders, which authorization must state the maximum amount of shares that may be allotted under it and specify the date on which it will expire, which must not be more than five years from the date on which the shareholder resolution is passed. An ordinary resolution was passed by shareholders at the Ensco 2017 Annual General Meeting to authorize the allotment of additional shares until the next annual general meeting of shareholders (or, if earlier, at the close of business on August 22, 2018). This authority will be increased if the Ensco General Allotment Authority Increase Proposal is passed at this meeting, but in any event, this authority will expire in 2018. As such, an ordinary resolution will be put to Ensco shareholders at Ensco's next annual general meeting seeking shareholder approval to renew the authority of the Ensco Board to allot shares for an additional one year term.

        English law also generally provides shareholders with pre-emption rights over new shares that are issued for cash. However, it is possible, where the board of directors is generally authorized to allot shares, to exclude pre-emption rights by a special resolution of the shareholders or by a provision in the articles of association. Such exclusion of pre-emption rights will commonly cease to have effect at the same time as the general allotment authority to which it relates is revoked or expires. If the general allotment authority is renewed, the authority excluding pre-emption rights may also be renewed by a special resolution of the shareholders. Special resolutions were passed, in conjunction with an allotment authority at the Ensco 2017 Annual General Meeting, to disapply pre-emption rights until the next annual general meeting of shareholders (or, if earlier, at the close of business on August 22, 2018). These authorities will be increased if the Ensco General Disapplication of Pre-emptive Rights Proposal and/or the Ensco Specified Disapplication of Pre-emptive Rights Proposal are passed at this meeting, but in any event, these authorities will expire in 2018. As such, special resolutions will be put to Ensco shareholders at Ensco's next annual general meeting seeking shareholder approval to renew the authority of the Ensco Board to disapply pre-emption rights for an additional one year term.

        English law prohibits Ensco from conducting "on-market purchases" as Ensco Class A ordinary shares will not be traded on a recognized investment exchange in the United Kingdom. English law also generally prohibits a company from repurchasing its own shares by way of "off-market purchases" without the approval by a special resolution of the shareholders of the terms of the contract by which the purchase(s) is affected. Such approval may only last for a maximum period of five years after the date on which the resolution is passed. A special resolution was passed at Ensco's annual shareholder meeting in May 2013 to permit Ensco to make "off-market" purchases of its own shares pursuant to certain purchase agreements for a five-year term.

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        Ensco cannot provide any assurances that situations will not arise where such shareholder approval requirements for any of these actions would deprive its shareholders of substantial benefits.

The Ensco Articles of Association contain anti-takeover provisions.

        Certain provisions of the Ensco Articles of Association have anti-takeover effects, such as the ability to issue shares under the Rights Plan (as defined therein). These provisions are intended to ensure that any takeover or change of control of Ensco is conducted in an orderly manner, all shareholders of Ensco are treated equally and fairly and receive an optimum price for their shares and the long-term success of Ensco is safeguarded. Under English law, it may not be possible to implement these provisions in all circumstances.

Ensco is not subject to the United Kingdom's Code on Takeovers and Mergers (the "Takeover Code").

        The Takeover Code only applies to an offer for a public company that is registered in the United Kingdom (or the Channel Islands or the Isle of Man) and the securities of which are not admitted to trading on a regulated market in the United Kingdom (or the Channel Islands or the Isle of Man) if the company is considered by the takeover panel (the "Panel") to have its place of central management and control in the United Kingdom (or the Channel Islands or the Isle of Man). This is known as the "residency test." The test for central management and control under the Takeover Code is different from that used by the U.K. tax authorities. Under the Takeover Code, the Panel will look to where the majority of the directors of the company are residents for the purposes of determining where the company has its place of central management and control. Accordingly, the Panel has previously indicated that the Takeover Code does not apply to Ensco and Ensco shareholders therefore do not have the benefit of the protections the Takeover Code affords, including, but not limited to, the requirement that a person who acquires an interest in shares carrying 30% or more of the voting rights in Ensco must make a cash offer to all other shareholders at the highest price paid in the 12 months before the offer was announced.

English law requires that Ensco meet certain additional financial requirements before declaring dividends and returning funds to shareholders.

        Under English law, Ensco is only able to declare dividends and return funds to its shareholders out of the accumulated distributable reserves on its statutory balance sheet. Distributable reserves are a company's accumulated, realized profits, so far as not previously utilized by distribution or capitalization, less its accumulated, realized losses, so far as not previously written off in a reduction or reorganization of capital duly made. Realized profits are created through the remittance of profits of certain subsidiaries to Ensco in the form of dividends.

        English law also provides that a public company can only make a distribution if, among other things (a) the amount of its net assets (that is, the total excess of assets over liabilities) is not less than the total of its called up share capital and non-distributable reserves and (b) if, and to the extent that, the distribution does not reduce the amount of its net assets to less than that total.

        Ensco may be unable to remit the profits of Ensco's subsidiaries in a timely or tax efficient manner. If at any time Ensco does not have sufficient distributable reserves to declare and pay quarterly dividends, Ensco may undertake a reduction in the capital, in addition to the reduction in capital taken in 2014, to reduce the amount of share capital and non-distributable reserves and to create a corresponding increase in distributable reserves out of which future distributions to shareholders can be made. To comply with English law, a reduction of capital would be subject to (a) approval of shareholders at a general meeting by special resolution; (b) confirmation by an order of the English Courts and (c) the Court order being delivered to and registered by the Registrar of Companies in England. If Ensco were to pursue a reduction of capital of Ensco as a course of action, and failed to obtain the necessary approvals from shareholders and the English Courts, Ensco may undertake other efforts to allow Ensco to declare dividends and return funds to shareholders.

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CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTS

        This joint proxy statement/prospectus and the documents incorporated herein by reference contain forward-looking statements within the meaning of Section 27A of the Securities Act and Section 21E of the Exchange Act. These forward-looking statements are identified as any statement that does not relate strictly to historical or current facts. They use words such as "anticipate," "believe," "intend," "plan," "projection," "forecast," "strategy," "position," "continue," "estimate," "expect," "may," or the negative of those terms or other variations of them or comparable terminology. In particular, statements, express or implied, concerning expected financial performance; expected impact of the merger and any synergies or cost-savings associated therewith; dividends; expected utilization, day rates, revenues, revenue efficiency, operating expenses, contract terms, contract backlog, capital expenditures, insurance, financing and funding; the timing of availability, delivery, mobilization, contract commencement or relocation or other movement of rigs and the timing thereof; future rig construction (including construction in progress and completion thereof), enhancement, upgrade or repair and timing and cost thereof, including startup post-idle costs; the suitability of rigs for future contracts; remaining rig useful lives; the offshore drilling market, including supply and demand, customer drilling programs, stacking of rigs, effects of new rigs on the market and effects of declines in commodity prices; general market, business and industry conditions, trends and outlook; future operations; the impact of increasing regulatory complexity; our program to high-grade the rig fleet by investing in new equipment and divesting selected assets and underutilized rigs; expense management; and the likely outcome of litigation, legal proceedings, investigations or insurance or other claims or contract disputes and the timing thereof. Forward-looking statements are not guarantees of performance. They involve risks, uncertainties and assumptions. Future actions, conditions or events and future results of operations may differ materially from those expressed in these forward-looking statements. Many of the factors that will determine actual results are beyond the ability of Ensco or Atwood to control or predict. Specific factors which could cause actual results to differ from those in the forward-looking statements include:

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        Unless expressly stated otherwise, forward-looking statements are based on the expectations and beliefs of the respective managements of Ensco and Atwood, based on information currently available, concerning future events affecting Ensco and Atwood. Although Ensco and Atwood believe that these forward-looking statements are based on reasonable assumptions, they are subject to uncertainties and factors related to Ensco's and Atwood's operations and business environments, all of which are difficult to predict and many of which are beyond Ensco's and Atwood's control. Any or all of the forward-looking statements in this joint proxy statement/prospectus may turn out to be wrong. They can be affected by inaccurate assumptions or by known or unknown risks and uncertainties. The foregoing list of factors should not be construed to be exhaustive. Many factors mentioned in this joint proxy statement/prospectus, including the risks outlined under the caption "Risk Factors" contained in Ensco's and Atwood's Exchange Act reports incorporated herein by reference, will be important in determining future results, and actual future results may vary materially. There is no assurance that the actions, events or results of the forward-looking statements will occur, or, if any of them do, when they will occur or what effect they will have on Ensco's and Atwood's results of operations, financial condition, cash flows or distributions. In view of these uncertainties, Ensco and Atwood caution that investors should not place undue reliance on any forward-looking statements. Further, any forward-looking statement speaks only as of the date on which it is made, and, except as required by law, Ensco and Atwood undertake no obligation to update or revise any forward-looking statement to reflect events or circumstances after the date on which it is made or to reflect new information or the occurrence of anticipated or unanticipated events or circumstances.

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THE ENSCO GENERAL MEETING

Date, Time, Place and Purpose of the Ensco General Meeting

        A general meeting of the shareholders of Ensco will be held at the offices of Slaughter and May, One Bunhill Row, London EC1Y 8YY, England, at 3:00 P.M. (London time) on October 5, 2017.

        You will be asked to consider and pass the four proposals below.

ORDINARY RESOLUTIONS

SPECIAL RESOLUTIONS

Ensco Board Recommendation

        The Ensco Board has unanimously determined that the form, terms and provisions of the merger agreement and the transactions contemplated thereby, including the merger and the allotment and issuance of the Ensco Class A ordinary shares, are advisable, fair and reasonable to and in the best

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interests of Ensco and its shareholders. The Ensco Board recommends that the Ensco shareholders vote:

Who Can Vote at the Ensco General Meeting

        Ensco shareholders who owned Class A ordinary shares at the close of business on August 23, 2017, the Ensco record date, are qualified to receive notice of, attend and vote at the Ensco general meeting or, subject to the Ensco Articles of Association, any adjournments or postponements thereof. For a period of 10 days prior to the Ensco general meeting, a list of all shareholders of record entitled to vote at the Ensco general meeting will be on file at Ensco's principal executive offices, 6 Chesterfield Gardens, London, W1J 5BQ, United Kingdom, and will be available for inspection at the Ensco general meeting for any purpose relevant to the Ensco general meeting. Changes to entries on the register after the record date will be disregarded in determining the rights of any person to attend or vote at the Ensco general meeting.

        On August 17, 2017, there were 303,979,543 Ensco Class A ordinary shares outstanding and entitled to vote at the Ensco general meeting. As of the Ensco record date, directors and executive officers of Ensco and its affiliates had the right to vote approximately 1,903,037 Ensco Class A common shares, or 0.63% of the outstanding Ensco Class A common shares on that date.

        Each Ensco Class A ordinary share is entitled to one vote on each matter to be voted on at the Ensco general meeting.

Vote Required for Approval; Quorum

        As a U.K. company publicly traded on the NYSE, Ensco shareholder approval of the Ensco Merger Consideration Proposal is subject to the shareholder approval requirements under both the Companies Act 2006 and NYSE rules. The Ensco Merger Consideration Proposal is being proposed as an ordinary resolution. Assuming a quorum is present, such proposal will be approved for purposes of the Companies Act 2006 and NYSE rules if a majority of the votes cast are cast in favor thereof. The Ensco General Allotment Authority Increase Proposal will be proposed as an ordinary resolution and, assuming a quorum is present, will be approved if a majority of the votes cast are cast in favor thereof. Each of the Ensco General Disapplication of Pre-emptive Rights Proposal and the Ensco Specified Disapplication of Pre-emptive Rights Proposal will be proposed as a special resolution, which means, assuming a quorum is present, each such proposal will be approved if at least 75% of the votes cast are cast in favor thereof.

        Approval of the Ensco Merger Consideration Proposal is required for completion of the merger. Approval of the Ensco General Allotment Authority Increase Proposal, the Ensco General Disapplication of Pre-emptive Rights Proposal or the Ensco Specified Disapplication of Pre-emptive Rights Proposal is not required in order to complete the merger.

        The Chairman may adjourn or postpone the meeting without notice other than announcement at the meeting. At the Ensco general meeting, holders of a majority of the outstanding Ensco Class A ordinary shares entitled to vote must be present, either in person or represented by proxy, to constitute a quorum. Abstentions and broker non-votes will be considered in determining the presence of a quorum. While abstentions and broker non-votes are not considered votes cast under the Companies Act 2006, under NYSE rules abstentions, but not broker non-votes, will be considered as votes cast for

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determining whether a sufficient number of votes have been cast on a particular proposal. As a result, for purposes of determining whether the Ensco Merger Consideration Proposal has been approved in accordance with the Companies Act 2006, abstentions and broker non-votes will not have any effect on the outcome of the vote. With respect to NYSE rules, abstentions will have the same effect as votes cast "AGAINST" the Ensco Merger Consideration Proposal and broker non-votes will not have any effect on the outcome of the vote. Abstentions and broker non-votes will have no effect on the outcome of the Ensco General Allotment Authority Increase Proposal, the Ensco General Disapplication of Pre-emptive Rights Proposal or the Ensco Specified Disapplication of Pre-emptive Rights Proposal.

        Your vote is very important. You are encouraged to vote as soon as possible and in any event by 11:59 p.m. Eastern Time on October 4, 2017 (or 11:59 p.m. Eastern Time on October 2, 2017 for employees holding Ensco Class A ordinary shares in the Ensco Savings Plan).

Manner of Voting

        If you are a "shareholder of record" of Ensco Class A ordinary shares, you may vote your shares in person at the Ensco general meeting (any resolution put to vote at a general meeting shall be decided on a poll) or, in accordance with provisions in the Companies Act 2006 and in accordance with the Ensco Articles of Association, you are entitled to appoint another person as your proxy to exercise all or any of your rights to attend, speak and vote at the Ensco general meeting and to appoint more than one proxy in relation to the Ensco general meeting (provided that each proxy is appointed to exercise the rights attached to a different share or shares held by you). Such proxy need not be a shareholder of record.

        After you have carefully read this joint proxy statement/prospectus, please respond by completing, signing and dating your proxy card or voting instruction card, as applicable, and returning it in the enclosed postage-paid envelope or, if available, by submitting your proxy or voting instructions by telephone or through the Internet as soon as possible so that your Ensco Class A ordinary shares will be represented and voted at the Ensco general meeting.

        If you are a shareholder of record, please sign the proxy card exactly as your name appears on the card. If shares are owned jointly, each joint owner should sign the proxy card. If a shareholder is a corporation, limited liability company or partnership, the proxy card should be signed in the full corporate, limited liability company or partnership name by a duly authorized person. If the proxy card is signed pursuant to a power of attorney or by an executor, administrator, trustee or guardian, please state the signatory's full title and provide a certificate or other proof of appointment.

        Please refer to your proxy card, voting instruction card or the information forwarded by your broker, bank, trust or other nominee to see which voting options are available to you.

        The Internet and telephone proxy submission procedures are designed to verify your holdings and to allow you to confirm that your instructions have been properly recorded.

        Neither the submission of a proxy or voting instructions, nor the method by which you submit a proxy or voting instructions will in any way limit your right to vote at the Ensco general meeting if you later decide to attend the meeting in person. If your Ensco Class A ordinary shares are held in the name of a broker, bank, trust or other nominee, you must either cause your Ensco Class A ordinary shares to be withdrawn or obtain a proxy, executed in your favor, from the holder of record of your Ensco Class A ordinary shares and obtain a proxy, executed in your favor, to be able to attend, speak and vote at the Ensco general meeting, although "street name" holders of Ensco Class A ordinary shares are permitted to attend the Ensco general meeting at the invitation of the Chairman.

        If you are a current or former Ensco employee who holds Ensco Class A ordinary shares in the Ensco Savings Plan, you will receive voting instructions from the trustee of the plan for Ensco Class A

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ordinary shares allocated to your account. If you fail to give voting instructions to the trustee of the plan, your Ensco Class A ordinary shares will be voted by such trustee in the same proportion and direction as Ensco Class A ordinary shares held by such trustee for which voting instructions were received. To allow sufficient time for voting by the trustee and administrator of the Ensco Savings Plan, your voting instructions for Ensco Class A ordinary shares held in the plan must be received by 11:59 P.M. Eastern Time on October 2, 2017.

        Voting instructions for Ensco Class A ordinary shares must be received by 11:59 p.m. Eastern Time on October 4, 2017 (or 11:59 p.m. Eastern Time on October 2, 2017 for employees holding Ensco Class A ordinary shares in the Ensco Savings Plan).

Revoking a Proxy

        You may revoke your proxy or voting instructions or change your vote at any time before the voting cutoff date in the case of holders of record and "street name" holders of Ensco Class A ordinary shares and before your proxy is voted at the Ensco general meeting in the case of shareholders of record. If your Ensco Class A ordinary shares are held in an account at a broker, bank, trust or other nominee and you desire to change your vote, you should contact your broker, bank, trust or other nominee for instructions on how to do so before the voting cutoff date.

        If you are a shareholder of record of Ensco Class A ordinary shares, you can revoke your proxy or voting instructions or change your vote after you have delivered your proxy or voting instructions in any of the three following ways:

        All Ensco Class A ordinary shares represented by valid proxies that Ensco receives through this solicitation, and that are not revoked, will be voted in accordance with your instructions on the proxy card.

        If you fail to make a specification on your proxy card as to how you want your shares voted before signing and returning it, your proxy will be voted "FOR" the Ensco Merger Consideration Proposal; "FOR" the Ensco General Allotment Authority Increase Proposal; "FOR" the Ensco General Disapplication of Pre-emptive Rights Proposal; and "FOR" the Ensco Specified Disapplication of Pre-emptive Rights Proposal.

Tabulation of the Votes

        Ensco will appoint an Inspector of Election for the Ensco general meeting to tabulate affirmative and negative votes and abstentions.

Solicitation of Proxies

        Ensco will bear its own costs and expenses incurred in connection with the filing, printing and mailing of this joint proxy statement/prospectus and the retention of any information agent or other service provider in connection with the merger. This proxy solicitation is being made by Ensco on behalf of the Ensco Board. Ensco has hired D.F. King & Co., Inc. and MacKenzie Partners, Inc. to

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assist in the solicitation of proxies. Ensco has agreed to pay D.F. King & Co., Inc. a fee of $20,000 plus payment of certain fees and expenses for its services to solicit proxies and voting instructions. In addition, Ensco has agreed to pay MacKenzie Partners, Inc. a fee of $35,000 plus payment of certain fees and expenses for its services to solicit proxies and voting instructions. In addition to this mailing, proxies may be solicited by directors, officers or employees of Ensco or its affiliates in person or by telephone or electronic transmission. None of the directors, officers or employees will be directly compensated for such services.

        In accordance with the regulations of the SEC and the NYSE, Ensco also will reimburse brokerage firms and other custodians, nominees and fiduciaries for their expenses incurred in sending proxies and proxy materials to beneficial owners of Ensco Class A ordinary shares.

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ENSCO PROPOSAL 1—MERGER CONSIDERATION PROPOSAL

        As discussed throughout this joint proxy statement/prospectus, Ensco is asking its shareholders to approve the allotment and issuance of Ensco Class A ordinary shares representing merger consideration. Holders of Ensco Class A ordinary shares should read carefully this joint proxy statement/prospectus in its entirety, including the annexes, for more detailed information concerning the merger agreement and the transactions contemplated thereby. In particular, holders of Ensco Class A ordinary shares are directed to the merger agreement, a copy of which is attached as Annex A to this joint proxy statement/prospectus.

        Accordingly, Ensco is requesting its shareholders adopt the following resolution, which is an ordinary resolution:

        "THAT, subject to the rules and listing standards of the New York Stock Exchange and to applicable rules and regulations of the U.S. Securities and Exchange Commission, pursuant to section 551 of the Companies Act 2006, and in addition to any subsisting authority conferred upon the Board of Directors of Ensco under that section, the Board of Directors of Ensco be and are hereby authorised unconditionally to allot and issue shares in the company as contemplated by the merger agreement, and to grant rights to subscribe for or convert any security into shares in the company, up to an aggregate nominal amount of $13,473,023, and so that the board may impose any limits or restrictions and make any arrangements which it considers necessary or appropriate to deal with treasury shares, fractional entitlements, record dates, legal, regulatory or practical problems in, or under the laws of, any territory or any other matter, such authority to apply until the close of business on August 22, 2018, provided that, during this period, the company may make offers and enter into agreements which would, or might, require shares to be allotted or rights to subscribe for or convert securities into shares to be granted after the authority ends and the board may allot shares or grant rights to subscribe for or convert securities into shares under any such offer or agreement as if the authority had not ended."

Vote Required and Ensco Board Recommendation

        Assuming a quorum is present, the affirmative vote of holders of at least a majority of the votes cast, either in person or by proxy, at the Ensco general meeting is required to approve the Ensco Merger Consideration Proposal.

        Completion of the merger is conditioned on, among other things, approval of the Ensco Merger Consideration Proposal. The allotment and issuance of the Ensco Class A ordinary shares will become effective only if the merger is completed. If authorized by our shareholders, this resolution would give the Ensco Board the authority to allot shares or grant rights to subscribe for or convert any securities into shares up to an aggregate nominal amount equal to $13,473,023. This amount represents approximately 44% of the issued share capital (excluding treasury shares) of Ensco as of August 17, 2017, the latest practicable date prior to publication of this joint proxy statement/prospectus. Allotments or issuances of ordinary shares for cash are subject to rights of pre-emption of the existing shareholders.

        See "Description of Ensco Class A Ordinary Shares."

        The Ensco Board has unanimously approved the merger agreement and the transactions contemplated thereby, including the merger, and unanimously recommends that you vote "FOR" the Ensco Merger Consideration Proposal. If no indication is given as to how you want your Ensco Class A ordinary shares to be voted, the persons designated as proxies will vote the proxies received "FOR" the Ensco Merger Consideration Proposal.

        See "The Merger—Ensco's Reasons for the Merger; Recommendation of the Ensco Board of Directors."

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ENSCO PROPOSAL 2—GENERAL ALLOTMENT AUTHORITY INCREASE PROPOSAL

        As a U.K. company governed in part by the Companies Act 2006, Ensco cannot issue new shares (other than in certain limited circumstances) without first obtaining approval from its shareholders. The Companies Act 2006 provides that this approval grants authority to the Ensco Board to allot shares in Ensco and to grant rights to subscribe for or convert any security of Ensco into shares in the capital of Ensco.

        At the annual general meeting of Ensco held on May 22, 2017, Ensco shareholders approved a resolution (based on the issued share capital of Ensco as at March 27, 2017, being the latest practicable date before the publication of the notice of Ensco's annual general meeting), to authorize the Ensco Board to allot shares and to grant rights to subscribe for or convert any security into shares:

such authority to be effective until the conclusion of Ensco's next annual general meeting (or, if earlier, at the close of business on August 22, 2018).

        Ensco expects to have an aggregate issued share capital of up to 438,709,772 Ensco Class A ordinary shares immediately following completion of the merger. Subject to approval of the merger and the new Ensco Class A ordinary shares being allotted as merger consideration, Ensco is seeking to obtain additional authority for the Ensco Board to allot shares to reflect the expected enlarged share capital of Ensco immediately following completion of the merger.

        Without this additional grant of authority from shareholders, the Ensco Board will only have the authority to issue shares up to the limits specified in the AGM Allotment Authority and the AGM Pre-Emptive Allotment Authority. Approval of the Ensco General Allotment Authority Increase Proposal will not, however, implicate any shareholder approval requirements of the NYSE for share issuances, such as for executive compensation purposes, certain financing transactions or in connection with acquisitions, and Ensco would continue to be subject to the requirements to obtain shareholder approval in those instances.

        Allotments or issuances of ordinary shares for cash are subject to rights of pre-emption of the existing Ensco shareholders. If the Ensco shareholders approve the Ensco General Disapplication of Pre-emptive Rights Proposal and the Ensco Specified Disapplication of Pre-emptive Rights Proposal described elsewhere in this joint proxy statement/prospectus at the meeting, those pre-emption rights will be disapplied to a limited extent as set forth in the Ensco General Disapplication of Pre-emptive Rights Proposal and the Ensco Specified Disapplication of Pre-emptive Rights Proposal for new issues of shares subject to the Ensco General Allotment Authority Increase Proposal.

        If authorized by Ensco shareholders, paragraph (A) of the Ensco General Allotment Authority Increase Proposal would give the Ensco Board, in addition to the authority granted to the Ensco Board pursuant to the AGM Allotment Authority and unused as of the date of this document, the authority to allot shares and grant rights to subscribe for or convert any securities into shares up to an aggregate nominal amount equal to $4,525,736. This amount, together with the nominal amount of shares specified in the AGM Allotment Authority and unused as of the date of this document, represents approximately 33.3% of the expected enlarged issued share capital (excluding treasury shares) of Ensco immediately following the completion of the merger.

        Paragraph (B) of the Ensco General Allotment Authority Increase Proposal would give the Ensco Board, in addition to the authority granted to the Ensco Board pursuant to the AGM Pre-Emptive

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Allotment Authority and unused as of the date of this document, authority to allot shares and grant rights to subscribe for or convert any securities into shares in connection with a rights issue or other similar issue in favor of ordinary shareholders up to an aggregate nominal amount equal to $9,024,968 (as reduced by the nominal amount of any shares issued under paragraph (A) of the Ensco General Allotment Authority Increase Proposal). This amount (before any reduction), together with the nominal amount of shares specified in the AGM Pre-Emptive Allotment Authority and unused as of the date of this document, represents approximately 66.6% of the expected enlarged issued share capital (excluding treasury shares) of Ensco immediately following the completion of the merger.

        Together, the aggregate nominal amount of any relevant securities issued under the authority conferred by paragraphs (A) and (B), when added to the authority conferred pursuant to the AGM Allotment Authority and the AGM Pre-Emptive Allotment Authority and unused as of the date of this document, represent an amount that is equal to approximately 66.6% of the aggregate nominal value of the expected enlarged issued share capital (excluding treasury shares) of Ensco immediately following the completion of the merger.

        The Ensco Board may exercise the authority to allot shares representing up to 33.3% (or 66.6% in connection with a rights issue or other similar issue) of the expected enlarged issued share capital of Ensco (excluding treasury shares) immediately following the completion of the merger. Such an allotment could be carried out in compliance with applicable U.K. law for various purposes including for example to raise additional capital, to reduce debt or increase liquidity as necessary. Any determination to exercise the authority to allot shares will be dependent upon market conditions and our profitability, liquidity, financial condition, market outlook, capital requirements and other factors the Ensco Board deems relevant.

        Accordingly, Ensco is requesting its shareholders adopt the following resolution, which is an ordinary resolution:

        "THAT, subject to and conditional on the Merger Consideration Proposal being passed and the Class A ordinary shares representing the merger consideration being allotted in connection with the merger, the board be generally and unconditionally authorised, in addition to all subsisting authorities, to allot shares in the company and to grant rights to subscribe for or convert any security into shares in the company:

such authority to apply until the conclusion of the next annual general meeting of shareholders (or, if earlier, at the close of business on August 22, 2018), but, in each case, during this period the company may make offers and enter into agreements which would, or might, require shares to be allotted or rights to subscribe for or convert securities into shares to be granted after the authority ends and the board may allot shares or

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grant rights to subscribe for or convert securities into shares under any such offer or agreement as if the authority had not ended."

Vote Required and Ensco Board Recommendation

        Assuming a quorum is present, the Ensco General Allotment Authority Increase Proposal will be passed if a majority of the votes cast at the meeting (in person or by proxy) are cast in favor of such proposal.

        Completion of the merger is not conditioned on approval of the Ensco General Allotment Authority Increase Proposal.

        The Ensco Board unanimously recommends that you vote "FOR" the Ensco General Allotment Authority Increase Proposal. If no indication is given as to how you want your Ensco Class A ordinary shares to be voted, the persons designated as proxies will vote the proxies received "FOR" the Ensco General Allotment Authority Increase Proposal.

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ENSCO PROPOSALS 3 AND 4—DISAPPLICATION OF PRE-EMPTIVE RIGHTS PROPOSALS

        As a U.K. company governed in part by the Companies Act 2006, before Ensco can raise additional capital through the issuance of ordinary shares of Ensco for cash, Ensco is required first to offer those shares to its current shareholders in proportion to their shareholdings. The Companies Act 2006 permits shareholders to waive, or disapply, those pre-emption rights. In addition, under U.K. law such pre-emption rights do not apply to any issuance of shares for non-cash consideration (including where shares are issued in exchange for other securities).

        At the annual general meeting of Ensco held on May 22, 2017, Ensco shareholders approved resolutions (based on the issued share capital of Ensco as at March 27, 2017, being the latest practicable date before the publication of the notice of Ensco's annual general meeting), to authorize the Ensco Board to:

such authority to be effective until the conclusion of Ensco's next annual general meeting (or, if earlier, at the close of business on August 22, 2018).

        Ensco expects to have an aggregate issued share capital of up to 438,709,772 Ensco Class A ordinary shares immediately following completion of the merger. Subject to approval of the merger and the new Ensco Class A ordinary shares being allotted as merger consideration, Ensco is seeking to obtain additional authority for the Ensco Board to allot shares for cash on a non-pre-emptive basis to reflect the expected enlarged share capital of Ensco immediately following completion of the merger.

        If Ensco shareholders approve the Ensco General Disapplication of Pre-emptive Rights Proposal and the Ensco Specified Disapplication of Pre-emptive Rights Proposal, and provided they approve the authority for the Ensco Board to allot shares pursuant to the Ensco General Allotment Authority Increase Proposal, their approval for each of the Ensco General Disapplication of Pre-emptive Rights Proposal and the Ensco Specified Disapplication of Pre-emptive Rights Proposal would be effective until the conclusion of the next annual general meeting of Ensco shareholders (or, if earlier, at the close of business on August 22, 2018).

        The Ensco General Disapplication of Pre-emptive Rights Proposal and the Ensco Specified Disapplication of Pre-emptive Rights Proposal would give the Ensco Board, in addition to the powers granted pursuant to the AGM General Pre-Emption Disapplication and the AGM Specified Pre-Emption Disapplication and unused as of the date of this document, the ability to raise additional capital by issuing ordinary shares and shares held in Ensco's treasury for cash free of the restriction in Section 561 of the Companies Act 2006.

        The power set out in the Ensco General Disapplication of Pre-emptive Rights Proposal would be limited to (a) allotments or sales in connection with pre-emptive offers and offers to holders of other equity securities if required by the rights of those securities or as the Ensco Board otherwise considers necessary, or (b) otherwise up to an aggregate nominal amount of $702,064 (which, when added to the authority conferred pursuant to the AGM General Pre-Emption Disapplication and unused as of the

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date of this document, represents approximately 5% of the expected enlarged issued share capital (excluding treasury shares) of Ensco immediately following the completion of the merger).

        In respect of the power referred to in (b) above, the Ensco Board confirms that it does not intend to issue shares in reliance on such authority if the cumulative usage of such authority within a rolling three-year period would be in excess of 7.5% of the issued share capital of Ensco (excluding treasury shares) without prior consultation with Ensco shareholders, except in connection with an acquisition or specified capital investment as described below in the Ensco Specified Disapplication of Pre-emptive Rights Proposal.

        The Ensco Specified Disapplication of Pre-emptive Rights Proposal is intended to give Ensco, in addition to the powers granted pursuant to the AGM Specified Pre-Emption Disapplication and unused as of the date of this document, additional flexibility to make non-pre-emptive issues of shares in connection with an acquisition or specified capital investment which is announced contemporaneously with the corresponding allotment, or which has taken place in the preceding six-month period and is disclosed in the announcement of the corresponding allotment. A specified capital investment means one or more specific capital investment related uses for the proceeds of an issuance of equity securities, in respect of which sufficient information regarding the effect of the transaction on Ensco, the assets which are the subject of the transaction and (where appropriate) the profits attributable to them is made available to Ensco shareholders to enable them to reach an assessment of the potential return.

        The power under the Ensco Specified Disapplication of Pre-emptive Rights Proposal is in addition to that proposed by the Ensco General Disapplication of Pre-emptive Rights Proposal and would be limited to an aggregate nominal amount of $675,560 (which, when added to the authority conferred pursuant to the AGM Specified Pre-Emption Disapplication and unused as of the date of this document, represents approximately 5% of the expected enlarged issued share capital (excluding treasury shares) of Ensco immediately following the completion of the merger).

        The powers under the Ensco General Disapplication of Pre-emptive Rights Proposal and the Ensco Specified Disapplication of Pre-emptive Rights Proposal would provide the Ensco Board with additional flexibility to pursue strategic transactions, raise capital and finance growth with equity.

Ensco Proposal 3—General Disapplication of Pre-emptive Rights Proposal

        For the reasons described above, Ensco is requesting its shareholders adopt the following resolution, which is a special resolution:

        "THAT, subject to and conditional on Proposals 1 and 2 being passed and the Class A ordinary shares representing the merger consideration being allotted in connection with the merger, the board shall be given power, in addition to all subsisting powers, to allot equity securities (as defined in the Companies Act) for cash under the authority given by Proposal 2 and/or to sell ordinary shares held by the company as treasury shares for cash as if Section 561 of Companies Act did not apply to any such allotment or sale, such power to be limited:

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such power to apply until the conclusion of the next annual general meeting of shareholders (or, if earlier, at the close of business on August 22, 2018); however, in each case, during this period the company may make offers, and enter into agreements, which would, or might, require equity securities to be allotted (and treasury shares to be sold) after the power ends and the board may allot equity securities (and sell treasury shares) under any such offer or agreement as if the power had not ended."

        Assuming a quorum is present, the Ensco General Disapplication of Pre-emptive Rights Proposal will be passed if at least 75% of the votes cast at the meeting (in person or by proxy) are cast in favor of this proposal.

        Completion of the merger is not conditioned on approval of the Ensco General Disapplication of Pre-emptive Rights Proposal.

        The Ensco Board unanimously recommends that you vote "FOR" the Ensco General Disapplication of Pre-emptive Rights Proposal. If no indication is given as to how you want your Ensco Class A ordinary shares to be voted, the persons designated as proxies will vote the proxies received "FOR" the Ensco General Disapplication of Pre-emptive Rights Proposal.

Ensco Proposal 4—Specified Disapplication of Pre-emptive Rights Proposal

        For the reasons described above, Ensco is requesting its shareholders adopt the following resolution, which is a special resolution:

        "THAT, subject to and conditional on Proposals 1 and 2 being passed and the Class A ordinary shares representing the merger consideration being allotted in connection with the merger, the board shall be given power, in addition to all subsisting powers and in addition to any power granted under Proposal 3 to allot equity securities (as defined in the Companies Act) for cash under the authority given pursuant to paragraph (A) of Proposal 2 and/or to sell ordinary shares held by the company as treasury shares for cash as if Section 561 of the Companies Act did not apply to any such allotment or sale, such power to be:

such power to apply until the conclusion of the next annual general meeting of shareholders (or, if earlier, at the close of business on August 22, 2018); however, in each case, during this period the company may make offers, and enter into agreements, which would, or might, require equity securities to be allotted (and treasury shares to be sold) after the power ends and the board may allot equity securities (and sell treasury shares) under any such offer or agreement as if the power had not ended."

        Assuming a quorum is present, the Ensco Specified Disapplication of Pre-emptive Rights Proposal will be passed if at least 75% of the votes cast at the meeting (in person or by proxy) are cast in favor of this proposal.

        Completion of the merger is not conditioned on approval of the Ensco Specified Disapplication of Pre-emptive Rights Proposal.

        The Ensco Board unanimously recommends that you vote "FOR" the Ensco Specified Disapplication of Pre-emptive Rights Proposal. If no indication is given as to how you want your Ensco Class A ordinary shares to be voted, the persons designated as proxies will vote the proxies received "FOR" the Ensco Specified Disapplication of Pre-emptive Rights Proposal.

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THE ATWOOD SPECIAL MEETING

Date, Time, Place and Purpose of the Atwood Special Meeting

        The Atwood special meeting will be held at 15011 Katy Freeway, First Floor, Houston, Texas 77094, at 9:00 A.M. (Houston time) on October 5, 2017 to consider and vote upon the following proposals:

Recommendation of the Atwood Board

        The Atwood Board has unanimously approved the merger agreement and the transactions contemplated thereby, including the merger. The Atwood Board determined that the merger, the execution, delivery and performance of the merger agreement and the transactions contemplated thereby are advisable and in the best interests of Atwood and its shareholders. The Atwood Board unanimously recommends that Atwood shareholders vote "FOR" the Atwood Merger Proposal. See "The Merger—Atwood's Reasons for the Merger; Recommendation of the Atwood Board of Directors" for a more detailed discussion of the Atwood Board's recommendation with respect to the Atwood Merger Proposal.

        In addition, the Atwood Board recommends the Atwood shareholders vote "FOR" the Atwood Compensatory Proposal and "FOR" the Atwood Adjournment Proposal.

Who Can Vote at the Atwood Special Meeting

        Atwood shareholders who owned Atwood common stock at the close of business on August 23, 2017, the Atwood record date, are qualified to receive notice of, attend and vote at the Atwood special meeting and any adjournment or postponement thereof. On August 17, 2017, there were 80,550,558 shares of Atwood common stock outstanding and entitled to vote at the Atwood special meeting.

        Each share of Atwood common stock is entitled to one vote on each matter to be voted on at the Atwood special meeting.

Vote Required for Approval; Quorum

        The presence at the Atwood special meeting of the holders, present in person or represented by proxy, of a majority of the outstanding shares of Atwood common stock entitled to vote at the meeting is necessary to constitute a quorum. Abstentions and broker non-votes will be counted for the purpose of determining whether a quorum is present.

        Under the TBOC, the affirmative vote of the holders of two-thirds of the outstanding shares of Atwood common stock entitled to vote as of the Atwood record date is required to approve the Atwood Merger Proposal. Because the required vote to approve the Atwood Merger Proposal is based upon the number of shares of Atwood common stock issued and outstanding on the Atwood record date and entitled to vote thereon, abstentions and broker non-votes, if any, will have the same effect as a vote cast "AGAINST" the Atwood Merger Proposal.

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        Assuming a quorum is present, the affirmative vote of holders of a majority of the votes cast is required to approve, on an advisory (non-binding) basis, the Atwood Compensatory Proposal. The vote to approve the Atwood Compensatory Proposal is not a condition to the completion of the merger, and the vote of Atwood's shareholders on this proposal is advisory in nature and will not be binding on Ensco or Atwood. Accordingly, regardless of the outcome of the advisory vote, if the Atwood Merger Proposal is approved and the merger is completed, specified compensation may be paid. For purposes of determining the number of votes cast with respect to such matter, abstentions and any broker non-votes will have no effect on the outcome of the Atwood Compensatory Proposal.

        Any adjournment of the Atwood special meeting pursuant to the Atwood Adjournment Proposal requires the affirmative vote of a majority of votes cast by the holders of shares of Atwood common stock present at the Atwood special meeting, in person or by proxy, and entitled to vote, whether or not a quorum exists. Abstentions and any broker non-votes will have no effect on the outcome of the Atwood Adjournment Proposal.

        As of August 17, 2017, directors and executive officers of Atwood and its affiliates, had the right to vote approximately 491,689 shares of Atwood common stock, or 0.61% of the outstanding Atwood common stock on that date. On the Atwood record date, there were 80,550,558 shares of Atwood common stock outstanding and entitled to vote at the Atwood special meeting.

        Approval of the Atwood Merger Proposal is required for completion of the merger. Approval of the other Atwood proposals set forth above is not required in order to complete the merger.

Proxies

        Each copy of this document mailed to holders of Atwood common stock is accompanied by a form of proxy with instructions for voting. If you hold stock in your name as a shareholder of record, you should complete and return the proxy card accompanying this document to ensure that your vote is counted at the Atwood special meeting, or at any adjournment or postponement of the Atwood special meeting, regardless of whether you plan to attend the Atwood special meeting. You may also authorize a proxy to vote your shares by telephone by calling 1-800-690-6903 or through the Internet at www.proxyvote.com.

        If you hold your stock in "street name" through a broker, bank, trust or other nominee, you must direct your broker, bank, trust or other nominee to vote in accordance with the instructions you have received from your broker, bank, trust or other nominee.

        If you are a shareholder of record of Atwood common stock, you can revoke your proxy or voting instructions or change your vote after you have delivered your proxy or voting instructions in any of the following ways:

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        Written notices of revocation and other communications about revoking your proxy should be addressed to:

Atwood Oceanics, Inc.
15011 Katy Freeway, Suite 800
Houston, TX 77094
Attention: Corporate Secretary

        All shares of Atwood common stock represented by valid proxies that Atwood receives through this solicitation, and that are not revoked, will be voted in accordance with your instructions on the proxy card.

        If you fail to make a specification on your proxy card as to how you want your shares voted before signing and returning it, your proxy will be voted "FOR" the Atwood Merger Proposal; "FOR" the Atwood Compensatory Proposal; and "FOR" the Atwood Adjournment Proposal.

        The Atwood Board is not currently aware of any business to be acted upon at the special meeting other than the matters described in this joint proxy statement/prospectus. If, however, other matters are properly brought before the special meeting, the persons appointed as proxies will have discretion to vote or act on those matters as in their judgment is in the best interest of Atwood and its shareholders.

Solicitation of Proxies

        Atwood will bear its own costs and expenses incurred in connection with the filing, printing and mailing of this joint proxy statement/prospectus and the retention of any information agent or other service provider in connection with the merger. This proxy solicitation is being made by Atwood on behalf of the Atwood Board. Atwood has hired Innisfree M&A Incorporated to assist in the solicitation of proxies. Atwood has agreed to pay Innisfree M&A Incorporated a fee of $25,000 plus payment of certain fees and expenses for its services to solicit proxies. In addition to this mailing, proxies may be solicited by directors, officers or employees of Atwood or its affiliates in person or by telephone or electronic transmission. None of the directors, officers or employees will be directly compensated for such services.

        In accordance with the regulations of the SEC and the NYSE, Atwood also will reimburse brokerage firms and other custodians, nominees and fiduciaries for their expenses incurred in sending proxies and proxy materials to beneficial owners of shares of Atwood common stock.

Attending the Meeting; Other Matters

        All holders of Atwood common stock, including shareholders of record and shareholders who hold their shares through brokers, banks, trusts, other nominees or any other holder of record, are invited to attend the Atwood special meeting. Shareholders of record can vote in person at the Atwood special meeting. If you are not a shareholder of record, you must obtain a proxy executed in your favor from the record holder of your shares, such as a broker, bank, trust or other nominee, to be able to vote in person at the Atwood special meeting. If you plan to attend the Atwood special meeting, you must hold your shares in your own name or have a letter from the record holder of your shares confirming your ownership and you must bring a form of personal photo identification with you in order to be admitted. Atwood reserves the right to refuse admittance to anyone without both proper proof of share ownership and proper photo identification.

        According to Atwood's bylaws, business to be conducted at a special meeting of Atwood shareholders may only be brought before the meeting pursuant to a notice of meeting, which must specify the purposes of the meeting. Accordingly, no matters other than the matters described in this document will be presented for action at the Atwood special meeting or at any adjournment or postponement of the Atwood special meeting.

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Adjournments and Postponements

        The Atwood special meeting may be adjourned pursuant to the Atwood Adjournment Proposal upon the affirmative vote of a majority of votes cast by the holders of Atwood common stock present at the Atwood special meeting, in person or by proxy, and entitled to vote, whether or not a quorum exists. Abstentions and any broker non-votes will have no effect on the outcome of the Atwood Adjournment Proposal under the Atwood bylaws. The Atwood special meeting may be adjourned without notice other than announcement at the meeting, except, if the adjournment is for more than 30 days or if after the adjournment a new record date is fixed for the reconvened meeting, a notice of the reconvened meeting must be given to each shareholder entitled to vote at such meeting.

        In addition, at any time prior to convening the Atwood special meeting, the Atwood Board may postpone the Atwood special meeting without the approval of Atwood's shareholders. If postponed, Atwood will publicly announce the new meeting date. Similar to adjournments, any postponement of the Atwood special meeting for the purpose of soliciting additional proxies will allow Atwood shareholders who have already sent in their proxies to revoke them at any time prior to their use.

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THE MERGER

Background of the Merger

        The Atwood Board, together with Atwood's management and with the assistance of Atwood's advisors, has periodically reviewed and considered various strategic opportunities available to Atwood and ways to enhance shareholder value and to enhance Atwood's performance and prospects, including in light of competitive, macroeconomic and industry developments. These reviews have included discussions as to whether the continued execution of Atwood's strategy as a stand-alone company or the possible sale of Atwood or certain of its assets to, or combination of Atwood with, a third party offered the best avenue to enhance shareholder value, and the potential benefits and risks of any such transaction. To assist Atwood in connection with the foregoing and to help Atwood respond to any proposals it may receive, Atwood formally engaged Goldman Sachs to act as Atwood's financial advisor on June 25, 2015.

        At a meeting on February 27, 2015 between Robert J. Saltiel, a director and the President and Chief Executive Officer of Atwood, and the CEO of Company A, the CEO of Company A indicated that combining Atwood and Company A could possibly make strategic sense for the two companies and their respective shareholders and if Atwood was ever interested in doing a transaction, Mr. Saltiel should contact him. Mr. Saltiel responded that Atwood was not focused on combination transactions at that time. Mr. Saltiel subsequently discussed the substance of the conversation with George S. Dotson, Chairman of the Atwood Board.

        The Ensco Board, together with Ensco's executive management team, periodically reviews strategies to improve Ensco's capital structure and optimize operational efficiency and to enhance Ensco's future growth opportunities and shareholder value. The review of future growth opportunities encompasses a range of potential strategies, including: improving Ensco's existing drilling rig fleet through capital improvements and investments in innovation; expanding the markets in which Ensco operates through joint ventures and/or strategic partnerships; acquisitions of individual or groups of drilling rigs; and larger scale business combinations and strategic transactions.

        During an Ensco Board meeting held on August 22, 2016, Carl G. Trowell, a director and the Chief Executive Officer and President of Ensco, and Patrick Carey Lowe, the Executive Vice President and Chief Operating Officer of Ensco, presented Atwood to the Ensco Board as one of several potential future growth opportunities and discussed with the Ensco Board Atwood's fleet quality, potential synergies, backlog, capital structure and geographic footprint. Given the attractiveness of the Atwood fleet and its complementary nature to the Ensco fleet, it was agreed that executive management would continue to assess Atwood along with other potential acquisition targets.

        During an executive session of an Atwood Board meeting held on August 25, 2016, the Atwood Board discussed the benefits of consolidation in the offshore drilling industry given the downturn in the industry and potential cost synergies that could be achievable in a combination transaction. Following the discussion of the merits, the Atwood Board authorized Mr. Saltiel to identify and explore potential opportunities for consolidation.

        At a breakfast meeting on September 9, 2016, Mr. Saltiel indicated to the CEO of Company A that the Atwood Board might be open to considering a combination between Company A and Atwood if it would be compelling to Atwood's shareholders. The CEO of Company A indicated that he would discuss the matter with the Company A board of directors.

        At a lunch meeting later that day, Mr. Saltiel indicated to the CEO of Company B that the Atwood Board might be open to considering a combination between Company B and Atwood if it would be compelling to Atwood's shareholders. The CEO of Company B indicated that Company B had not previously analyzed a combination with Atwood, and on September 19, 2016 he emailed Mr. Saltiel to state that his team was conducting preliminary analysis of a combination. Company B never followed up with any indication of interest in combining with Atwood.

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        At an industry event on November 1, 2016, the CEO of Company C approached Mr. Saltiel to indicate that Company C had analyzed a potential combination with Atwood given the complementary nature of their respective businesses, but that he did not believe the market conditions at the time were conducive for Company C to pursue a transaction. Company C never followed up with any indication of interest in combining with Atwood.

        During an executive session of an Atwood Board meeting held on November 17, 2016, Mr. Saltiel discussed his previous meetings with the CEOs of Company A, Company B and Company C. The Atwood Board discussed those meetings and the potential for continuing to explore other strategic alternatives.

        On January 26, 2017, Mark Smith, Senior Vice President and Chief Financial Officer of Atwood, met for lunch with the CFO of Company D. The CFO of Company D asked Mr. Smith if Atwood would be interested in a potential combination with Company D and if so, what type of consideration Atwood would accept in such a transaction. Mr. Smith stated that Atwood and the Atwood Board were open to exploring any strategic alternatives that would be compelling to the Atwood shareholders. Mr. Smith and the CFO of Company D agreed to inform the chief executive officers of their respective companies. Mr. Smith called Mr. Saltiel that evening to inform him of the meeting and what was discussed.

        During an Ensco Board meeting held on February 21, 2017, Mr. Trowell, Mr. Lowe and Jonathan Baksht, Senior Vice President and Chief Financial Officer, again presented Atwood along with a range of other strategic alternatives to the Ensco Board as part of its corporate strategy review and noted that Atwood had undertaken certain capital restructuring steps to improve its balance sheet.

        At a March 1, 2017 breakfast meeting, the CEO of Company D asked Mr. Saltiel if Atwood would be open to engaging in a corporate combination with Company D. Mr. Saltiel responded that Atwood and the Atwood Board were open to considering any strategic alternatives that are compelling to the Atwood shareholders. The CEO of Company D stated that he would follow up with Mr. Saltiel on this matter at a later date. Mr. Saltiel subsequently discussed the substance of the conversation with Mr. Dotson.

        In connection with a change in personnel on the Goldman Sachs team, Atwood and Goldman Sachs entered into a second engagement letter dated March 14, 2017.

        On April 13, 2017, Mr. Saltiel and the CEO of Company A had a telephone conversation in which Mr. Saltiel asked the CEO of Company A if Company A would have interest in acquiring certain of Atwood's assets if Atwood determined to pursue such a sale. The CEO of Company A followed up this phone call by leaving a voicemail with Mr. Saltiel stating that Company A would not be interested in acquiring solely those assets but would potentially be interested in a corporate combination. The CEO of Company A indicated that he would discuss it with the Company A board of directors at its next meeting.

        At an April 18, 2017 meeting between Mr. Saltiel and the CEO of Company D, the CEO of Company D stated that Company D would be prepared to make an all-stock proposal for Atwood representing an approximately 30% premium to Atwood's then current share price, or an implied value of approximately $10.40 per share of Atwood common stock on that date. Mr. Saltiel indicated that he would discuss any such proposal with the Atwood Board but that, given recent trading prices of the respective companies' shares, he did not believe the Atwood Board would find the proposed consideration sufficiently compelling to the Atwood shareholders. Mr. Saltiel subsequently discussed the substance of the conversation with Mr. Dotson.

        In light of the positive changes in the Atwood balance sheet, improving valuations and the belief that Atwood may be pursuing strategic options with other parties, Mr. Trowell called Mr. Saltiel on April 19, 2017 to express an interest in a potential acquisition of Atwood by Ensco. As a result of its

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periodic strategic review, the Ensco Board was open to considering a strategic combination with a partner that would provide a good strategic fit with Ensco and enhance shareholder value. The Ensco Board and Ensco's management believed that a combination with Atwood could enhance Ensco's asset and customer base and geographic scope at an attractive valuation. Ensco also believed that Atwood might consider such a combination in light of its declining backlog and contracting activity. Mr. Saltiel stated that Atwood and the Atwood Board were open to exploring any strategic alternatives that would be compelling to the Atwood shareholders.

        During the second half of April 2017 and the first part of May 2017, Ensco conducted a diligence review of Atwood's public filings and publicly available materials related to Atwood and its operations.

        On April 20, 2017, the CEO of Company A called Mr. Saltiel to inquire whether Atwood would potentially be interested in a combination with Company A. Mr. Saltiel stated that Atwood and the Atwood Board were open to exploring any strategic alternatives that would be compelling to the Atwood shareholders. There were no further discussions with Company A prior to the announcement of the merger, nor did Atwood enter into a confidentiality or standstill agreement with Company A.

        On April 25, 2017, the CEO of Company D sent Mr. Saltiel a non-binding indication of interest for Company D to combine with Atwood in which the Atwood shareholders would receive shares of Company D stock at an exchange ratio which valued Atwood at an implied equity value of $11.00 per share of Atwood common stock, a 40% premium to Atwood's April 24 closing stock price (the "Company D Proposal"). The Company D Proposal indicated that the transaction would not be subject to any financing contingency and contained a request for a 30-day exclusivity period for the parties to conduct due diligence and negotiate definitive agreements. The Company D Proposal requested a response from Atwood by May 8, 2017.

        On April 27, 2017, Atwood contacted Gibson, Dunn & Crutcher LLP ("Gibson Dunn") to assist Atwood in connection with the evaluation of the approaches described above, including the Company D Proposal, and on May 5, 2017 Atwood formally engaged Gibson Dunn to act as Atwood's legal counsel.

        On May 2, 2017, Mr. Saltiel called the CEO of Company D to inform him that, given Atwood management's focus on its upcoming earnings release and an industry conference, Atwood would need more time to analyze the Company D Proposal and respond. The CEO of Company D acknowledged Mr. Saltiel's request.

        On May 7, 2017, Goldman Sachs provided a letter to the Atwood Board disclosing certain relationships between Goldman Sachs and its affiliates and Atwood and Ensco. Such letter stated, among other things, that as of that date, none of Goldman Sachs' Investment Banking Division, funds in which Goldman Sachs' Investment Banking Division had a direct investment or funds managed by Goldman Sachs' Merchant Banking Division had a direct investment in the equity securities of Atwood or Ensco.

        The Atwood Board held a meeting on May 10, 2017 at which members of Atwood management, including Mr. Saltiel and Walter A. Baker, Atwood's Senior Vice President, General Counsel and Corporate Secretary, were present, along with representatives of Gibson Dunn and Goldman Sachs. Representatives of Gibson Dunn provided the Atwood Board with an overview of director responsibilities and fiduciary duties in the circumstances. Representatives of Goldman Sachs reviewed its preliminary financial analyses of Atwood and the Company D Proposal. The Atwood Board discussed the various alternatives presented and the reasonableness of different approaches. They also discussed relative valuations and views on the values of the consideration that could be offered by the other potential parties. Mr. Saltiel provided his views to the Atwood Board that a transaction with Company D based on the terms in the Company D Proposal would allow Atwood shareholders to participate in any recovery in the offshore drilling industry and the positive synergies that a

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combination with Company D would create. Mr. Saltiel recommended that Atwood provide a counter proposal to Company D in order to try to obtain increased value and for representation on Company D's board of at least two current Atwood directors. The Atwood Board concurred with Mr. Saltiel's recommendations and Mr. Saltiel informed the Atwood Board that he would keep it apprised of discussions with Company D. The Atwood Board also discussed whether to approach any of the other potential parties, including Company A and Ensco, and concluded that it would be disadvantageous to do so at that time due to potential risks of jeopardizing the Company D Proposal and reputational and operational risks if the information was made public that Atwood was approaching other parties about potential business combinations.

        On May 10, 2017, Mr. Saltiel called the CEO of Company D to provide a counter proposal to the Company D Proposal. Mr. Saltiel stated that Atwood would be open to considering an all-stock acquisition by Company D that valued Atwood at a 66.5% premium to Atwood's May 10 closing share price and which provided for two members of the Atwood Board to be nominated to the Company D board following the closing of the transaction. The CEO of Company D indicated that the proposed valuation was not in a range that Company D found acceptable.

        On May 11, 2017, Ensco retained Morgan Stanley to act as a financial advisor to Ensco in connection with a potential transaction with Atwood. On the same date, Ensco engaged Latham & Watkins LLP ("Latham") as its U.S. legal advisor and Slaughter and May ("Slaughter") as its U.K. legal advisor.

        Following its diligence efforts and discussions with Morgan Stanley, Ensco was prepared to submit an initial offer to Atwood. On May 12, 2017, Mr. Trowell and Paul E. Rowsey, III, Chairman of the Ensco Board, sent a non-binding indication of interest (the "Initial Ensco Indication of Interest") from Ensco addressed to Mr. Saltiel and Mr. Dotson proposing that Ensco and Atwood combine in an all-stock transaction in which the Atwood shareholders would receive 1.278 Ensco Class A ordinary shares for each share of Atwood common stock held by such holder, which valued Atwood at an implied equity value of $10.17 per Atwood share and reflected a 20.0% premium to Atwood's closing stock price on May 11, 2017. Following submission of the Initial Ensco Indication of Interest, several separate discussions were held among Mr. Rowsey, Mr. Trowell, Mr. Baksht and Michael T. McGuinty, Senior Vice President and General Counsel. Messrs. Rowsey and Trowell then updated the remaining Ensco Board members regarding the submission of the Initial Ensco Indication of Interest.

        On May 16, 2017, at the direction of the Atwood Board, representatives of Goldman Sachs called representatives of Company D's financial advisor to discuss Atwood's counterproposal of May 10, 2017. Company D's financial advisor reiterated that the proposed valuation was not in a range that Company D found acceptable and that Company D did not plan to revise its proposal at that time. There were no further discussions with Company D or its representatives prior to the announcement of the merger, nor did Atwood enter into a confidentiality or standstill agreement with Company D.

        On May 17, 2017, the Atwood Board held an executive session at which representatives of Gibson Dunn and Goldman Sachs were present. Mr. Saltiel and representatives of Goldman Sachs reviewed with the Atwood Board the Initial Ensco Indication of Interest. The representatives of Goldman Sachs reviewed its preliminary financial analyses of Atwood and the proposals from Ensco and Company D. The Atwood Board asked questions with respect to and discussed the respective businesses and prospects for each of Ensco and Company D and potential strategies for negotiating with both parties. Mr. Saltiel indicated that Ensco's all-stock proposal would require Ensco shareholder approval and that Atwood faced possible business disruption risks if Ensco shareholders did not approve a transaction. Mr. Saltiel proposed that he would contact Mr. Trowell to explain that Ensco's proposal was at a lower valuation than another opportunity and that if Ensco made a revised proposal, Atwood's preference would be for the proposal to include both stock and cash, with the stock portion below the threshold requiring an Ensco shareholder vote. The Atwood Board concurred with Mr. Saltiel's proposal.

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        On May 19, 2017, Mr. Saltiel informed Mr. Trowell on the telephone that the Initial Ensco Indication of Interest represented a lower valuation for Atwood than another opportunity which Atwood was exploring. Mr. Saltiel also indicated that Atwood would prefer to engage in a transaction with increased closing certainty which did not require a shareholder vote from Ensco and therefore Mr. Saltiel suggested that any revised proposal from Ensco include both stock and cash, with the stock portion below the threshold requiring an Ensco shareholder vote.

        On May 20, 2017, at the direction of the Atwood Board, representatives of Goldman Sachs had a call with representatives of Morgan Stanley to discuss the Ensco proposal. Representatives of Goldman Sachs indicated that value and deal certainty, particularly around the Ensco shareholder vote, were important considerations for Atwood. Representatives of Goldman Sachs also discussed with Morgan Stanley that the Initial Ensco Indication of Interest represented a lower valuation for Atwood than another opportunity which Atwood was exploring. Representatives of Goldman Sachs reiterated Atwood's preference that any revised proposal from Ensco include both stock and cash, with the stock portion below the threshold requiring an Ensco shareholder vote.

        On May 22, 2017, the Atwood Board held a meeting at which members of Atwood's management, including Mr. Saltiel and Mr. Baker, acting as Secretary of the meeting, and representatives of Gibson Dunn were present. Mr. Saltiel updated the Atwood Board on discussions with Mr. Trowell and Morgan Stanley. The Atwood Board discussed with representatives of Gibson Dunn the possibility of negotiating a reverse termination fee to be paid by Ensco in the event that the Ensco shareholders did not approve the merger, including the feasibility of such a fee compensating Atwood for any loss in value in the event the merger did not close. Mr. Saltiel then discussed the status of discussions with Company D. Company D had not responded to Atwood's counterproposal since Mr. Saltiel had spoken with the CEO of Company D on May 10, 2017 and Goldman Sachs' follow up call with Company D's financial advisor on May 16, 2017, and at then current stock prices, the Company D Proposal represented a 14% premium, a substantial decrease compared to a 40% premium at the time it was made. Mr. Saltiel proposed to wait until Atwood had heard back from Ensco before potentially approaching Company D again, and the Atwood Board concurred with this suggested approach.

        On May 23, 2017, in connection with a regularly scheduled meeting of the Ensco Board, Messrs. Trowell and Baksht discussed the potential acquisition of Atwood with the Ensco Board and the potential benefits of combining the companies. Mr. Trowell updated the Ensco Board on his May 19, 2017 discussion with Mr. Saltiel. During the Ensco Board meeting, representatives of Morgan Stanley also made a presentation to the Ensco Board regarding a possible business combination with Atwood. Following discussions with Ensco management and Morgan Stanley, the Ensco Board authorized management to submit a revised indication of interest (the "Revised Ensco Indication of Interest"). Subsequent to the Ensco Board meeting, Mr. Trowell stated to Mr. Saltiel on a telephone call that Ensco planned to send a revised indication of interest that represented Ensco's best and final proposal.

        On May 24, 2017, Mr. Trowell and Mr. Rowsey sent the Revised Ensco Indication of Interest to Mr. Saltiel and Mr. Dotson. The Revised Ensco Indication of Interest proposed an all-stock transaction in which the Atwood shareholders would receive 1.60 Ensco Class A ordinary shares per share of Atwood common stock, which valued Atwood at an implied equity value of $12.19 per Atwood share and reflected a 37% premium to Atwood's closing stock price on May 23, 2017. The Revised Ensco Indication of Interest indicated that, in order to address Atwood's desire to maximize deal certainty, Ensco proposed to include a $50 million reverse termination fee payable by Ensco to Atwood in the event that Ensco's shareholders did not approve the merger. The Revised Ensco Indication of Interest requested exclusivity through May 29, 2017 to complete due diligence and negotiate definitive agreements.

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        Following Atwood's receipt of the Revised Ensco Indication of Interest, members of Atwood's management, including Messrs. Saltiel and Baker, held a teleconference on May 24, 2017 with representatives of Goldman Sachs and Gibson Dunn to discuss the receipt of the proposal and to prepare for the meeting of the Atwood Board which was to be held the following day.

        On May 25, 2017, the Atwood Board held a meeting at which members of Atwood's management, including Mr. Saltiel and Mr. Baker, acting as Secretary of the meeting, and representatives of Gibson Dunn and Goldman Sachs were present. Mr. Saltiel and representatives of Goldman Sachs updated the Atwood Board on the Revised Ensco Indication of Interest and discussions with Messrs. Trowell and Baksht. Mr. Saltiel noted that Mr. Trowell informed him that the Ensco proposal represented its best and final proposal for a strategic transaction. Mr. Saltiel described the terms of the Revised Ensco Indication of Interest including the fact that (i) the proposal was for an all-stock transaction, (ii) Ensco had increased the exchange ratio of the merger consideration from 1.278 Ensco Class A ordinary shares per Atwood share to 1.60 Ensco Class A ordinary shares per Atwood share, (iii) Ensco had committed to a $50 million reverse termination fee in the event that Ensco shareholders failed to approve the transaction, (iv) Ensco had committed to a short timeline to negotiate definitive agreements by May 29, 2017 and (v) Ensco's proposal would expire the next day, May 26, 2017 at 12:00 p.m. (Houston time). Representatives of Goldman Sachs recounted their conversations with Mr. Baksht and representatives of Morgan Stanley who stated that the Revised Ensco Indication of Interest represented Ensco's best and final proposal and that if Atwood did not engage in negotiations with Ensco on the terms included in the Revised Ensco Indication of Interest before the proposal expired, Ensco was likely to pursue other alternatives. Representatives of Gibson Dunn indicated that Latham had informed them that the Ensco Board had determined that the $50 million reverse termination fee was reasonable under the circumstances but that the Ensco Board was not prepared to support a higher fee. The Atwood Board discussed the continuing viability of a transaction with Company D. Mr. Saltiel stated that Company D had ceased engaging in discussions since its proposal of April 25, 2017, that Atwood risked losing the Ensco proposal if it reinitiated contact with Company D and that Ensco's most recent proposal represented a substantially higher premium than the Company D Proposal. The Atwood Board concurred. The Atwood Board also discussed the comparative financial performances and balance sheets of Ensco and Atwood. Mr. Saltiel suggested that a combination with Ensco could be more advantageous to the Atwood shareholders than the Company D Proposal but would need to be confirmed through due diligence. Mr. Saltiel proposed engaging in discussions and due diligence with Ensco and agreeing to a customary exclusivity agreement with Ensco through May 29, 2017 with the intent to negotiate definitive agreements in the timeframe proposed by Ensco. Mr. Saltiel recommended that Atwood propose representation on the Ensco Board of at least two current Atwood directors. The Atwood Board concurred with Mr. Saltiel's proposals.

        After the Atwood Board meeting on May 25, 2017, Mr. Saltiel called Mr. Trowell to discuss entering into a confidentiality agreement.

        On May 25, 2017, Ensco, Atwood and their respective legal counsels, Latham and Gibson Dunn, negotiated a confidentiality agreement. On May 25, 2017, Ensco and Atwood entered into a confidentiality agreement that did not contain standstill or employee non-solicitation provisions. The parties agreed that they would execute an addendum to the confidentiality agreement containing customary standstill and employee non-solicitation provisions before the parties commenced negotiations of a definitive merger agreement.

        On May 25, 2017, Mr. Saltiel, Mr. Trowell and representatives of their respective financial advisors at Goldman Sachs and Morgan Stanley participated in a teleconference to conduct preliminary due diligence and Mr. Saltiel and Mr. Trowell discussed Ensco's vision and strategy for the combined company.

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        On May 26, 2017, Mr. Saltiel called Mr. Trowell and indicated that Atwood would be willing to proceed with diligence and the negotiation of a definitive merger agreement on the basis of the terms in the Revised Indication of Interest if Ensco would appoint two Atwood directors to the Ensco Board to reflect Atwood's pro forma ownership of the combined company.

        On May 26, 2017, Atwood formally engaged Goldman Sachs to act as Atwood's financial advisor in connection with the prospective transaction.

        On May 26, 2017, following discussions with members of the Ensco Board, Mr. Trowell sent a final indication of interest (the "Final Ensco Indication of Interest") to Mr. Saltiel, which the parties executed on that day. The Final Ensco Indication of Interest maintained Ensco's non-binding proposal (i) to acquire Atwood in all-stock transaction in which each share of Atwood common stock would be exchange for 1.60 Ensco Class A ordinary shares and (ii) to pay a reverse termination fee of $50 million in the event the Ensco shareholders did not approve the merger. The Final Ensco Indication of Interest also stated that Ensco would appoint two Atwood directors, to be agreed by the parties, as non-executive directors to the Ensco Board upon consummation of the merger. The Final Ensco Indication of Interest contained binding customary exclusivity provisions, and Atwood agreed to negotiate exclusively with Ensco through May 29, 2017.

        On May 26, 2017, Ensco and Atwood entered into an addendum to the confidentiality agreement containing customary standstill and employee non-solicitation provisions.

        On the evening of May 26, 2017, Latham sent Gibson Dunn a draft of the merger agreement that proposed, among other provisions: (i) to expand the Ensco Board to include two Atwood non-employee directors; (ii) that the parties make substantially reciprocal representations and warranties; (iii) limited restrictions on Ensco's conduct of business prior to closing, which were not reciprocal, and more expansive restrictions to which Atwood would be subject; (iv) a no-shop covenant only applicable to Atwood; (v) a $50 million termination fee payable by Ensco under certain circumstances including if the Ensco shareholders did not approve the merger; and (vi) a termination fee payable by Atwood equal to 4% of implied equity value payable under certain circumstances, including if Atwood breached its no-shop covenants.

        On May 27, 2017, Mr. Saltiel and Mr. Trowell discussed open issues in the merger agreement, including the lack of reciprocal no-shop provisions and reciprocal restrictions on Ensco's conduct of business and the size of the termination fee payable by Atwood. Mr. Saltiel indicated that Gibson Dunn would be sending a revised merger agreement to Latham reflecting Atwood's positions later that evening. Mr. Trowell advised that he would work with his team to resolve the open issues.

        Following the call between Messrs. Saltiel and Trowell, overnight on May 27, 2017, Gibson Dunn sent Latham a revised draft of the merger agreement that proposed, among other provisions: (i) substantially reciprocal restrictions on Ensco's conduct of business prior to closing to those to which Atwood would be subject; (ii) mutual no-shop covenants; and (iii) that the size of the Atwood termination fee was left open to discussion.

        On May 27, 2017, Ensco retained DNB Capital LLC and HSBC Securities (USA) Inc. as co-financial advisors to provide financial advisory services to Ensco's management related to the potential transaction with Atwood and to assist Ensco in structuring the combined company's anticipated capitalization following such transaction.

        From May 27, 2017 through May 29, 2017, representatives of Ensco and Atwood, along with their respective legal advisors, exchanged due diligence materials and conducted various due diligence calls relating to, among other things, financial and accounting, compliance, environmental, legal and human resources matters. Over the same period representatives of Ensco, Atwood and their respective legal advisors also conducted multiple teleconference calls to discuss tax diligence and the tax consequences of the proposed transaction to Atwood shareholders.

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        During the course of the day on May 28, 2017, Atwood, Ensco and their respective advisors also held discussions regarding the merger agreement.

        On the evening of May 28, 2017, Latham sent Gibson Dunn a revised draft of the merger agreement that proposed, among other provisions: (i) reduced restrictions on Ensco's conduct of business prior to closing as compared to those contained in the Gibson Dunn draft merger agreement of May 27, 2017; and (ii) that the size of the Atwood termination fee was left open to discussion.

        On May 29, 2017, Mr. Saltiel called Mr. Trowell to discuss open issues in the merger agreement, including those matters described above. During the course of the day on May 29, 2017, Atwood, Ensco and their respective advisors engaged in negotiations regarding, and Latham and Gibson Dunn exchanged revised drafts of, the merger agreement and continued to engage in due diligence.

        Following the foregoing negotiations and resolution of the points at issue, in the early evening of May 29, 2017, Latham delivered to Gibson Dunn a substantially final draft of the merger agreement, a copy of which both Ensco and Atwood provided to their respective boards of directors. The draft reflected an agreement in principle among the parties on all material points including the size of the Atwood termination fee.

        On May 29, 2017, the Atwood Board held a meeting at which members of Atwood's management, including Messrs. Saltiel and Smith and Mr. Baker, acting as Secretary of the meeting, and representatives of Gibson Dunn and Goldman Sachs were present. Messrs. Saltiel, Baker and Smith and Gibson Dunn provided the Atwood Board with information on the material terms of the merger agreement with Ensco. During the meeting, representatives of Goldman Sachs reviewed its financial analysis of the proposed transaction and delivered to the Atwood Board its oral opinion, which representatives of Goldman Sachs confirmed by delivery of a written opinion dated May 29, 2017, that, as of that date and based upon and subject to the factors and assumptions set forth therein, the exchange ratio pursuant to the merger agreement was fair from a financial point of view to the holders (other than Ensco and its affiliates) of shares of Atwood common stock, as more fully described below in the section entitled "—Opinion of Financial Advisor to Atwood." Gibson Dunn reviewed with the Atwood Board its fiduciary duties and the key provisions of the merger agreement. The Atwood Board asked questions and discussed its duties, the merger agreement provisions and related matters. After discussion in which the Atwood Board considered the factors discussed further in the section entitled "—Atwood's Reasons for the Merger; Recommendation of the Atwood Board of Directors," the members of the Atwood Board unanimously approved the merger agreement and the transactions contemplated by the merger agreement. The Atwood Board also deemed it advisable to consummate the merger on the terms and subject to the conditions set forth in the merger agreement, and to recommend that Atwood shareholders vote to approve the merger and the other transactions contemplated by the merger agreement.

        On May 29, 2017, the Ensco Board held a meeting, together with its legal and financial advisors, to discuss the proposed transaction. At this meeting, among other matters, Messrs. Trowell, Lowe, Baksht and McGuinty discussed with the Ensco Board the diligence conducted with respect to Atwood and Latham reviewed with the Ensco Board the terms of the merger agreement. Representatives of Morgan Stanley rendered its oral opinion to the Ensco Board, subsequently confirmed by delivery of a written opinion, dated May 29, 2017, that, as of the date of such opinion, and based upon and subject to the various assumptions made, procedures followed, matters considered and qualifications and limitations on the scope of review undertaken as set forth in its written opinion, the exchange ratio pursuant to the merger agreement was fair from a financial point of view to Ensco. Following a discussion regarding the proposed transaction by the Ensco Board, the Ensco Board unanimously determined that the form, terms and provisions of the merger agreement and the transactions contemplated thereby, including the merger and the allotment and issuance of the Ensco Class A ordinary shares, were advisable, fair and reasonable to and in the best interests of Ensco and its shareholders. The Ensco Board unanimously determined to recommend that Ensco shareholders vote to approve the Ensco Merger Consideration Proposal.

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        Atwood and Ensco then executed the merger agreement later that evening.

        Prior to the opening of markets in the United States on May 30, 2017, Atwood and Ensco jointly announced the merger and held a joint investor conference call.

Ensco's Reasons for the Merger; Recommendation of the Ensco Board of Directors

        By vote at a meeting held on May 29, 2017, the Ensco Board unanimously determined that the form, terms and provisions of the merger agreement and the transactions contemplated thereby, including the merger and the allotment and issuance of the Ensco Class A ordinary shares, are advisable, fair and reasonable to and in the best interests of Ensco and its shareholders. The Ensco Board unanimously recommends that Ensco shareholders vote "FOR" the Ensco Merger Consideration Proposal.

        In deciding to approve the merger agreement and to recommend that Ensco shareholders vote to approve the Ensco Merger Consideration Proposal, the Ensco Board consulted with Ensco's management and financial and legal advisors and considered several factors.

        The Ensco Board considered a number of factors when evaluating the merger, many of which support the Ensco Board's determination that the merger is advisable, fair and reasonable to and in the best interest of Ensco and its shareholders. The Ensco Board considered these factors as a whole and without assigning relative weights to each such factor, and overall considered the relevant factors to be favorable to, and in support of, its determinations and recommendations. These factors included:

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        The Ensco Board considered additional information concerning the merger as a whole and without assigning relative weights to each such item, and overall considered the relevant factors to be favorable to, and in support of, its determinations and recommendations. This information included:

        The Ensco Board also considered a variety of risks and other potentially negative factors concerning the merger agreement and the transactions contemplated thereby, including the merger. These factors included:

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        This discussion of the information and factors considered by the Ensco Board in reaching its conclusion and recommendations includes all of the material factors considered by the Ensco Board but is not intended to be exhaustive and is not provided in any specific order or ranking. In view of the wide variety of factors considered by the Ensco Board in evaluating the merger agreement and the transactions contemplated thereby, including the merger, and the complexity of these matters, the Ensco Board did not find it practicable to, and did not attempt to, quantify, rank or otherwise assign relative weight to those factors. In addition, different members of the Ensco Board may have given different weight to different factors. The Ensco Board did not reach any specific conclusion with respect to any of the factors considered and instead conducted an overall analysis of such factors and determined that, in the aggregate, the potential benefits considered outweighed the potential risks or possible negative consequences of approving the merger agreement and the allotment and issuance of Ensco Class A ordinary shares pursuant to the merger agreement.

        It should be noted that this explanation of the reasoning of the Ensco Board and all other information presented in this section is forward-looking in nature and, therefore, should be read in light of the factors discussed under the heading "Cautionary Statement Regarding Forward-Looking Statements."

Atwood's Reasons for the Merger; Recommendation of the Atwood Board of Directors

        By a vote at a meeting held on May 29, 2017, the Atwood Board unanimously: (1) determined that the execution, delivery and performance of the merger agreement and the consummation of the transactions contemplated by the merger agreement were advisable and in the best interests of Atwood and its shareholders; (2) approved the merger agreement and the transactions contemplated thereby, including the merger; (3) recommended that Atwood shareholders vote their shares in favor of the merger; and (4) directed that the merger agreement be submitted to a vote at a meeting of Atwood shareholders.

        The Atwood Board unanimously recommends that the Atwood shareholders vote "FOR" the Atwood Merger Proposal at the Atwood special meeting and vote "FOR" all other proposals.

        In evaluating the merger, the Atwood Board consulted with and received the advice of Atwood's management and legal and financial advisors and, in reaching its determination and recommendation to enter into the merger agreement, the Atwood Board considered a number of factors, including, but not limited to, the following:

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        In the course of its deliberations, the Atwood Board also considered a variety of risks and other countervailing factors related to entering into the merger agreement, including, but not limited to, the following:

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        The Atwood Board considered all of these factors as a whole and, on balance, concluded that they supported a determination to approve the merger agreement. The foregoing discussion of the information and factors considered by the Atwood Board is not exhaustive, but rather is meant to include the material factors that the Atwood Board considered. In view of the wide variety of factors, both positive and negative, considered by the Atwood Board in connection with its evaluation of the proposed merger and the complexity of these matters, the Atwood Board did not consider it practical to, nor did it attempt to, quantify, rank or otherwise assign relative weights to the specific factors that it considered in reaching its decision. The Atwood Board evaluated the factors described above, among others, and collectively reached a consensus that the proposed merger was advisable and in the best interests of Atwood and its shareholders. In considering the factors described above and any other factors that are not presented, individual members of the Atwood Board may have viewed factors differently or given different weight or merit to different factors. In addition, the factors described above are not presented in any order of priority.

        In considering the recommendation of the Atwood Board to approve the Atwood Merger Proposal, Atwood shareholders should be aware that the executive officers and directors of Atwood have certain interests in the merger that may be different from, or in addition to, the interests of Atwood shareholders generally. The Atwood Board was aware of these interests and considered them when approving the merger agreement and recommending that Atwood shareholders vote to approve the Atwood Merger Proposal. See "—Atwood's Directors and Officers Have Financial Interests in the Merger."

        It should be noted that this explanation of the reasoning of the Atwood Board and all other information presented in this section is forward-looking in nature and, therefore, should be read in light of the factors discussed under the heading "Cautionary Statement Regarding Forward-Looking Statements."

Opinion of Financial Advisor to Ensco

        The Ensco Board retained Morgan Stanley to provide it with financial advisory services in connection with the proposed merger and to provide a financial opinion. The Ensco Board selected Morgan Stanley to act as its financial advisor based on Morgan Stanley's qualifications, expertise and reputation and its knowledge of the business and affairs of Ensco. On May 29, 2017, at a meeting of the Ensco Board, Morgan Stanley rendered its oral opinion, subsequently confirmed by delivery of a written opinion, dated May 29, 2017, that, as of that date and based upon and subject to the various assumptions made, procedures followed, matters considered and qualifications and limitations on the scope of review undertaken by Morgan Stanley as set forth in the written opinion, the exchange ratio pursuant to the merger agreement was fair from a financial point of view to Ensco.

        The full text of the written opinion of Morgan Stanley delivered to the Ensco Board, dated as of May 29, 2017, is attached to this joint proxy statement/prospectus as Annex B and is incorporated herein by reference in its entirety. You should read Morgan Stanley's opinion and this summary of Morgan Stanley's opinion carefully and in their entirety for a discussion of the assumptions made, procedures followed, matters considered and qualifications and limitations on the scope of the review undertaken by Morgan Stanley in rendering its opinion. This summary is qualified in its entirety by

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reference to the full text of such opinion. Morgan Stanley's opinion was directed to the Ensco Board, in its capacity as such, and addressed only the fairness from a financial point of view to Ensco of the exchange ratio pursuant to the merger agreement as of the date of such opinion. Morgan Stanley's opinion did not address any other aspects or implications of the merger. Morgan Stanley's opinion did not in any manner address the price at which the Ensco Class A ordinary shares would trade following the merger or at any time, and Morgan Stanley expressed no opinion or recommendation to any holder of Ensco Class A ordinary shares or Atwood common stock as to how such holder should vote at the Ensco general meeting or the Atwood special meeting, respectively, or whether to take any other action with respect to the merger.

        For purposes of rendering its opinion, Morgan Stanley, among other things:

        Morgan Stanley assumed and relied upon, without independent verification, the accuracy and completeness of the information that was publicly available or supplied or otherwise made available to it by Atwood and Ensco, and formed a substantial basis for its opinion. With respect to the financial projections, including information relating to certain strategic, financial and operational benefits

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anticipated from the merger, Morgan Stanley assumed that they had been reasonably prepared on bases reflecting the best currently available estimates and judgments of the respective managements of Atwood and Ensco of the future financial performance of Atwood and Ensco. For purposes of its analysis, Morgan Stanley, at the direction of Ensco, relied on financial projections relating to Atwood and Ensco, in each case prepared by the management of Ensco. Morgan Stanley was advised by Ensco and assumed, with Ensco's consent, that the projections prepared by the management of Ensco were a reasonable basis upon which to evaluate the business and financial prospects of Ensco and Atwood. Morgan Stanley expressed no view as to such projections or the assumptions on which they were based. Morgan Stanley relied upon, without independent verification, the assessment by the management of Ensco of: (i) the strategic, financial and other benefits expected to result from the merger; (ii) the timing and risks associated with the integration of Atwood and Ensco; and (iii) Ensco's ability to retain key employees of Atwood and Ensco, respectively. In addition, Morgan Stanley assumed that the merger would be consummated in accordance with the terms set forth in the merger agreement without any waiver, amendment or delay of any terms or conditions, including, among other things, that the definitive merger agreement would not differ in any material respect from the draft thereof furnished to it. Morgan Stanley assumed that in connection with the receipt of all the necessary governmental, regulatory or other approvals and consents required for the proposed merger, no delays, limitations, conditions or restrictions would be imposed that would have a material adverse effect on the contemplated benefits expected to be derived in the proposed merger. Morgan Stanley is not a legal, tax, or regulatory advisor. Morgan Stanley is a financial advisor only and relied upon, without independent verification, the assessment of Ensco and Atwood and their legal, tax or regulatory advisors with respect to legal, tax, or regulatory matters. Morgan Stanley did not perform any tax assessment in connection with the merger. Morgan Stanley expressed no opinion with respect to the fairness of the amount or nature of the compensation to any of Atwood's officers, directors or employees, or any class of such persons, relative to the consideration to be paid to the holders of shares of Atwood common stock in the transaction. Morgan Stanley did not make any independent valuation or appraisal of the assets or liabilities of Atwood or Ensco, nor was it furnished with any such valuations or appraisals. Morgan Stanley's opinion did not address the relative merits of the merger as compared to any other alternative business transaction, or other alternatives, or whether or not such alternatives could be achieved or are available. Morgan Stanley's opinion was necessarily based on financial, economic, market and other conditions as in effect on, and the information made available to it as of, the date of the opinion. Events occurring after such date may affect Morgan Stanley's opinion and the assumptions used in preparing it, and Morgan Stanley did not assume any obligation to update, revise or reaffirm its opinion.

Summary of Financial Analyses of Morgan Stanley

        The following is a summary of the material financial analyses performed by Morgan Stanley in connection with its oral opinion and the preparation of its written opinion to the Ensco Board, each dated as of May 29, 2017. The following summary is not a complete description of the financial analyses performed and factors considered by Morgan Stanley in connection with its opinion, nor does the order of analyses described represent the relative importance or weight given to those analyses. Except as otherwise noted, the following quantitative information, to the extent that it is based on market data, is based on market data as it existed on or before May 26, 2017, the most recent trading day prior to Morgan Stanley's presentation to the Ensco Board of its financial analysis on May 29, 2017. Some of these summaries of financial analyses include information presented in tabular format. In order to fully understand the financial analyses used by Morgan Stanley, the tables must be read together with the text of each summary. The tables alone do not constitute a complete description of the financial analyses. The analyses listed in the tables and described below must be considered as a whole. Assessing any portion of such analyses and of the factors reviewed, without considering all analyses and factors, could create a misleading or incomplete view of the process underlying Morgan

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Stanley's opinion. Furthermore, mathematical analysis (such as determining the average or median) is not in itself a meaningful method of using the data referred to below.

        In performing the financial analyses summarized below and in arriving at its opinion, at the direction of the Ensco Board, Morgan Stanley utilized and relied upon certain financial projections relating to Atwood and Ensco, each provided by the management of Ensco and which are described below. In addition, Morgan Stanley utilized and relied upon the number of issued and outstanding shares of Atwood provided by management of Atwood.

        As part of the financial projections, Ensco management provided, and Morgan Stanley relied upon with the consent of the Ensco Board, Ensco Management Case A and Ensco Management Case B (the "Ensco financial forecasts"). Ensco management informed Morgan Stanley that Ensco Management Case B was more reflective of the then-current market outlook than Ensco Management Case A, and Morgan Stanley relied upon such information with the consent of the Ensco Board. The Ensco financial forecasts are more fully described in the section entitled "—Certain Unaudited Financial Forecasts Prepared by the Management of Ensco."

Useful Life Discounted Cash Flow Analysis

        Morgan Stanley performed a discounted cash flow analysis, which is designed to provide an implied value of a company by calculating the present value of the estimated future cash flows and terminal value of that company. In the "useful life" discounted cash flow analysis, Morgan Stanley performed a discounted cash flow analysis on each of Atwood and Ensco, respectively, based on the unlevered cash flows generated by Atwood's and Ensco's fleet of rigs through the estimated end of their useful lives as estimated by the management of Ensco (which are estimated to extend through 2055 for Atwood and through 2050 for Ensco).

Atwood Useful Life Discounted Cash Flow Analysis

        With respect to Atwood, Morgan Stanley calculated a range of implied total equity values of Atwood and values per share of Atwood common stock based on estimates of future cash flows from April 1, 2017 through June 30, 2055. Morgan Stanley performed this analysis on the estimated future cash flows of Atwood contained in Ensco Management Case A and Ensco Management Case B. Morgan Stanley first calculated the estimated unlevered free cash flows (calculated as earnings before interest, taxes, and depreciation and amortization, which is referred to in this section as EBITDA, less capital expenditures and unlevered taxes, and adjusted for any changes in working capital). The projected unlevered free cash flows were discounted to March 31, 2017 using discount rates ranging from 8.1% to 9.3% for the period between April 1, 2017 through December 31, 2020 based on Morgan Stanley's estimate of Atwood's weighted average cost of capital ("WACC") for such period, and the projected unlevered cash flows for the period from January 1, 2021 through June 30, 2055 were discounted to March 31, 2017 using discount rates ranging from 8.4% to 9.6% based on Morgan Stanley's estimate of Atwood's WACC for such period. The range of discount rates used for such period differed from that used for the period ending December 31, 2020 as a result of an assumed increase in the cost of debt. Morgan Stanley then deducted from the implied aggregate value ranges Atwood's estimated gross debt and minority interest and added Atwood's cash and cash equivalents as of March 31, 2017. Aggregate values also included the then-current estimate of the value of capital spare parts of Atwood as estimated by Ensco management.

        Based on the above-described analysis, Morgan Stanley derived a range of implied values per share for Atwood as of March 31, 2017 for each of Ensco Management Case A and Ensco Management Case B of $25.68 to $30.90 and $13.33 to $17.09, respectively.

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Ensco Useful Life Discounted Cash Flow Analysis

        With respect to Ensco, Morgan Stanley calculated a range of implied total equity values of Ensco and values per Ensco Class A ordinary share based on estimates of future cash flows of Ensco from April 1, 2017 through December 31, 2050. Morgan Stanley performed this analysis on the estimated future cash flows contained in Ensco Management Case A and Ensco Management Case B. Morgan Stanley first calculated the estimated unlevered free cash flows (calculated as EBITDA less capital expenditures and unlevered taxes, and adjusted for any changes in working capital). The projected unlevered free cash flows were discounted to March 31, 2017 using discount rates ranging from 7.5% to 8.5% for the period between April 1, 2017 through December 31, 2020 based on Morgan Stanley's estimate of Ensco's WACC for such period, and the projected unlevered cash flows for the period from January 1, 2021 through December 31, 2050 were discounted to present value using discount rates ranging from 7.7% to 8.8% based on Morgan Stanley's estimate of Ensco's WACC for such period. The range of discount rates used for such period differed from that used for the period ending December 31, 2020 as a result of an assumed redemption of notes. With the cost of debt lower than the cost of equity, the assumed redemption lowered the debt-to-capitalization ratio, therefore increasing the weighted average cost of capital. Morgan Stanley then deducted from the implied aggregate value ranges Ensco's estimated gross debt and minority interest and added Ensco's cash and cash equivalents as of March 31, 2017 (adjusted for open market repurchases of debt in April 2017). Aggregate values also included the then-current estimate of the value of capital spare parts of Ensco as estimated by Ensco management.

        Based on the above-described analysis, Morgan Stanley derived a range of implied values per Ensco Class A ordinary share as of March 31, 2017 for each of Ensco Management Case A and Ensco Management Case B of $19.07 to $22.57 and $10.12 to $12.63, respectively.

Exchange Ratio Implied by Useful Life Discounted Cash Flow Analysis

        Morgan Stanley calculated the exchange ratio ranges implied by the useful life discounted cash flow analyses. Morgan Stanley compared the lowest implied per share value for Atwood common stock to the highest implied per share value for Ensco Class A ordinary shares to derive the lowest exchange ratio implied by the analyses. Similarly, Morgan Stanley compared the highest implied per share value for Atwood common stock to the lowest implied per share value for Ensco Class A ordinary shares to derive the highest exchange ratio implied by the analyses. The implied exchange ratio ranges resulting from the analysis, which Morgan Stanley noted did not include synergies, was 1.14x to 1.62x for Ensco Management Case A and 1.06x to 1.69x for Ensco Management Case B. Morgan Stanley noted that the merger agreement provided for an exchange ratio of 1.60x.

10-Year Discounted Cash Flow Analysis

        Morgan Stanley also performed a discounted cash flow analysis on both Atwood and Ensco based on estimates of future cash flows from April 1, 2017 through March 31, 2027 and calculated a terminal value at the end of such projection period. Management of Ensco informed Morgan Stanley that Ensco Management Case B was more reflective of the then-current market outlook than Ensco Management Case A, and as a result, Morgan Stanley conducted the discounted cash flow analysis using only Ensco Management Case B.

Atwood 10-Year Discounted Cash Flow Analysis

        With respect to Atwood, Morgan Stanley calculated a range of implied total equity values of Atwood and values per share of Atwood common stock based on estimates of future cash flows for Atwood from April 1, 2017 to March 31, 2027. Morgan Stanley first calculated the estimated unlevered free cash flows (calculated as EBITDA, less capital expenditures and unlevered taxes and adjusted for

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any changes in working capital) of Atwood based on estimates by the management of Ensco. Morgan Stanley then calculated a terminal value range for Atwood by applying a multiple of aggregate value (defined as market capitalization plus total debt and minority interests and less cash and cash equivalents) to estimated EBITDA for the twelve months ending March 31, 2028 of 5.0x to 8.0x. This range was derived based on Morgan Stanley's professional judgment after calculating the aggregate value to EBITDA multiples for the twelve months following the date of measurement (the "NTM EBITDA") that Atwood common shares had traded at from May 2012 to May 2017, which resulted in an average aggregate value to NTM EBITDA (based on publicly available estimates) of 6.9x for such period. The projected unlevered free cash flows were discounted to March 31, 2017 using discount rates ranging from 8.1% to 9.3% for the period from April 1, 2017 through December 31, 2020 based on Morgan Stanley's estimate of Atwood's WACC for such period, and the projected unlevered cash flows for the period from January 1, 2021 through March 31, 2027 and terminal value were discounted to March 31, 2017 using discount rates ranging from 8.4% to 9.6% based on Morgan Stanley's estimate of Atwood's WACC for such period. The range of discount rates used for such period differed from that used for the period ending December 31, 2020 as a result of an assumed increase in the cost of debt. Morgan Stanley then deducted from the implied aggregate value ranges Atwood's estimated gross debt and minority interest and added Atwood's cash and cash equivalents as of March 31, 2017. Aggregate values also included the then-current estimate of the value of capital spare parts of Atwood as estimated by Ensco management.

        Based on the above-described analysis, Morgan Stanley derived a range of implied values per share for Atwood as of March 31, 2017 for Ensco Management Case B of $9.21 to $17.68.

Ensco 10-Year Discounted Cash Flow Analysis

        With respect to Ensco, Morgan Stanley calculated a range of implied total equity values of Ensco and values per Ensco Class A ordinary share based on estimates of future cash flows for Ensco from April 1, 2017 to March 31, 2027. Morgan Stanley first calculated the estimated unlevered free cash flows (calculated as EBITDA, less capital expenditures and unlevered taxes and adjusted for any changes in working capital) of Ensco based on estimates by the management of Ensco. Morgan Stanley then calculated a terminal value range for Ensco by applying a multiple of aggregate value to estimated EBITDA for the twelve months ending March 31, 2028 of 5.0x to 8.0x. This range was derived based on Morgan Stanley's professional judgment after calculating the NTM EBITDA that Ensco common shares had traded at from May 2012 to May 2017, which resulted in an average aggregate value to NTM EBITDA (based on publicly available estimates) of 6.6x for such period. The projected unlevered free cash flows were discounted to March 31, 2017 using discount rates ranging from 7.5% to 8.5% for the period from April 1, 2017 through December 31, 2020 based on Morgan Stanley's estimate of Ensco's WACC for such period, and the projected unlevered cash flows for the period from January 1, 2021 through March 31, 2027 and terminal value were discounted to March 31, 2017 using discount rates ranging from 7.7% to 8.8% based on Morgan Stanley's estimate of Ensco's WACC for such period. The range of discount rates used for such period differed from that used for the period ending December 31, 2020 as a result of an assumed redemption of notes. With the cost of debt lower than the cost of equity, the assumed redemption lowered the debt-to-capitalization ratio, therefore increasing the weighted average cost of capital. Morgan Stanley then deducted from the implied aggregate value ranges Ensco's estimated gross debt and minority interest and added Ensco's cash and cash equivalents as of March 31, 2017 (adjusted for open market repurchases of debt in April 2017). Aggregate values also included the then-current estimate of the value of capital spare parts of Ensco as estimated by Ensco management.

        Based on the above-described analysis, Morgan Stanley derived a range of implied values per Ensco Class A ordinary share as of March 31, 2017 for Ensco Management Case B of $8.58 to $15.43.

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Exchange Ratio Implied by 10-Year Discounted Cash Flow Analysis

        Morgan Stanley calculated the exchange ratio ranges implied by the discounted cash flow analyses. Morgan Stanley compared the lowest implied per share value for Atwood common stock to the highest implied per share value for Ensco Class A ordinary shares to derive the lowest exchange ratio implied by the analyses. Similarly, Morgan Stanley compared the highest implied per share value for Atwood common stock to the lowest implied per share value for Ensco Class A ordinary shares to derive the highest exchange ratio implied by the analyses. The implied exchange ratio ranges resulting from the analysis, which Morgan Stanley noted did not include synergies, was 0.60x to 2.06x for Ensco Management Case B. Morgan Stanley noted that the merger agreement provided for an exchange ratio of 1.60x.

Discounted Equity Value Analysis

        For each of Atwood and Ensco, Morgan Stanley performed a discounted equity value analysis, which is designed to provide an indication of the present value of a theoretical future value of a company's equity as a function of such company's estimated future EBITDA.

        Management of Ensco informed Morgan Stanley that Ensco Management Case B was more reflective of the then-current market outlook than Ensco Management Case A, and as a result, Morgan Stanley conducted the discounted equity value analysis using only Ensco Management Case B.

Atwood Discounted Equity Value

        Morgan Stanley calculated the discounted equity value per share of Atwood common stock as of March 31, 2017. To calculate the discounted equity value per share of Atwood common stock, Morgan Stanley utilized calendar year 2022 EBITDA based on the financial forecasts provided by Ensco. Morgan Stanley calculated the future equity value per share of Atwood common stock at January 1, 2022 by applying an aggregate value to EBITDA multiple of 5.0x to 8.0x to the estimated calendar year 2022 EBITDA based on the financial forecasts provided by Ensco. This reference range was based on Morgan Stanley's professional judgment and derived in the manner described under "—Atwood 10-Year Discounted Cash Flow Analysis." The resulting per share equity values were then discounted to March 31, 2017 using a cost of equity for Atwood of 17.0% based on Morgan Stanley's estimate of Atwood's then-current cost of equity. Morgan Stanley added the then-current estimate of the per share value of capital spare parts of Atwood as estimated by Ensco management to Atwood's implied share price. This analysis resulted in a range of implied values per share for Atwood of $6.84 to $13.95.

Ensco Discounted Equity Value

        Morgan Stanley calculated the discounted equity value per Ensco Class A ordinary share as of March 31, 2017. To calculate the discounted equity value per Ensco Class A ordinary share, Morgan Stanley utilized calendar year 2022 EBITDA based on the financial forecasts provided by Ensco. Morgan Stanley calculated the future equity value per Ensco Class A ordinary share at January 1, 2022 by applying an aggregate value to EBITDA multiple of 5.0x to 8.0x to the estimated calendar year 2022 EBITDA based on the financial forecasts provided by Ensco. This reference range was based on Morgan Stanley's professional judgment and derived in the manner described under "—Ensco 10-Year Discounted Cash Flow Analysis." The resulting per share equity values were then discounted to March 31, 2017 using cost of equity for Ensco of 15.6% based on Morgan Stanley's estimate of Ensco's then-current cost of equity. Morgan Stanley added the then-current estimate of the per share value of capital spare parts of Ensco and estimated present value of dividends on each Ensco common share, each as estimated by Ensco management to Ensco's implied share price. This analysis resulted in a range of implied values per Ensco Class A ordinary share of $4.76 to $10.20.

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Exchange Ratio Implied by Discounted Equity Value Analysis

        Morgan Stanley then calculated the exchange ratio range implied by the discounted equity value analysis. Morgan Stanley compared the lowest implied equity value per share for Atwood common stock to the highest implied equity value per Ensco Class A ordinary share to derive the lowest exchange ratio implied by the discounted equity value analyses. Similarly, Morgan Stanley compared the highest implied equity value per share for Atwood common stock to the lowest implied equity value per Ensco Class A ordinary share to derive the highest exchange ratio implied by the discounted equity value analyses. The implied exchange ratio range resulting from this analysis, which Morgan Stanley noted did not include synergies, was 0.67x to 2.93x. Morgan Stanley noted that the merger agreement provided for an exchange ratio of 1.60x.

Trading Multiple Analysis

        Morgan Stanley performed a trading multiple analysis to determine the ratio of the closing stock price per share of Atwood common stock and per Ensco Class A ordinary share, in each case as of May 26, 2017, to Atwood's and Ensco's respective then current net asset value per share ("NAV"). Morgan Stanley refers to this statistic as "Price/NAV." The Price/NAVs of Atwood and Ensco were also compared against the Price/NAVs of four comparable public companies: Diamond Offshore Drilling, Inc., Transocean Ltd., Rowan Companies plc, and Noble Corporation plc. These companies were chosen based on Morgan Stanley's knowledge of the industry and because they have businesses that may be considered similar to that of Atwood and Ensco. The NAVs utilized were based on an average of publicly available analyst research reports disclosing discounted cash flow, sum-of-the-parts or net asset value-based valuations. The Price/NAVs were as follows:

Company
  Price / NAV (as of May 26, 2017)  

Atwood

    0.66x  

Ensco

    0.63x  

Diamond Offshore Drilling, Inc. 

    0.82x  

Transocean Ltd. 

    0.79x  

Rowan Companies plc

    0.72x  

Noble Corporation plc

    0.55x  

        Based on this analysis and its professional judgment, Morgan Stanley selected a reference range of Price/NAV of 0.6x to 1.0x, and applied the reference range to the NAVs of Atwood and Ensco, respectively. Based on an average of publicly available analyst reports disclosing discounted cash flow, sum-of-the-parts or net asset value-based valuations, the NAV of Atwood was calculated to be $12.20 and the NAV of Ensco was calculated to be $10.57. Morgan Stanley also included the then-current estimate of the per share value of capital spare parts of Atwood and Ensco as estimated by Ensco management to Atwood and Ensco's implied share price, respectively. This analysis resulted in an implied share price range of $8.49 to $13.37 per share of Atwood common stock and $7.22 to $11.45 per Ensco Class A ordinary share.

        Morgan Stanley then calculated the exchange ratio implied by the trading multiple analysis. Morgan Stanley compared the lowest implied equity value per share for Atwood common stock to the highest implied equity value per Ensco Class A ordinary share to derive the lowest exchange ratio implied by the trading multiple analysis. Similarly, Morgan Stanley compared the highest implied equity value per share for Atwood common stock to the lowest implied equity value per Ensco Class A ordinary share to derive the highest exchange ratio implied by the trading multiple analysis. The implied exchange ratio reference range resulting from this analysis, which Morgan Stanley noted did not include synergies, was 0.74x to 1.85x. Morgan Stanley noted that the merger agreement provided for an exchange ratio of 1.60x.

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        No company utilized in the trading multiple analysis is identical to Atwood or Ensco and hence the foregoing summary and underlying financial analyses involved complex considerations and judgments concerning differences in financial and operating characteristics and other factors that could affect the public trading or other values of the companies to which Atwood and Ensco were compared, respectively. In evaluating comparable companies, Morgan Stanley made judgments and assumptions with regard to industry performance, general business, economic, market and financial conditions and other matters, many of which are beyond the control of Atwood and Ensco.

Pro Forma Discounted Cash Flow Accretion Analysis

        Morgan Stanley performed a pro forma discounted cash flow accretion analysis, which is designed to compare a range of pro forma useful life discounted cash flow values per share based on the 1.60x exchange ratio provided for in the merger agreement to the range of Ensco useful life discounted cash flow values per share calculated on a standalone basis (see "—Ensco Useful Life Discounted Cash Flow Analysis").

        Morgan Stanley calculated a range of pro forma implied aggregate values by summing the present values of the useful life unlevered free cash flows of Atwood, Ensco and synergies (based on assumed run-rate synergies of $65 million, as directed by Ensco management). For the purposes of the pro forma discounted cash flow accretion analysis, the unlevered free cash flows of Ensco, Atwood and synergies were discounted to March 31, 2017 using discount rates ranging from 7.5% to 8.5% for the period between April 1, 2017 through December 31, 2020 based on Morgan Stanley's estimate of Ensco's WACC for such period, and the projected unlevered cash flows for the forecast period thereafter were discounted to present value using discount rates ranging from 7.7% to 8.8% based on Morgan Stanley's estimate of Ensco's WACC for such period. Morgan Stanley then adjusted the total pro forma implied aggregate value ranges by Ensco's and Atwood's estimated gross debt, minority interest and cash and cash equivalents as of March 31, 2017 (with Ensco's gross debt and cash and cash equivalents adjusted for open market repurchases of debt in April 2017). Aggregate values also included the then-current estimate of the value of capital spare parts of Atwood and Ensco as estimated by Ensco management. To derive a range of pro forma useful life discounted cash flow values per share, such amount was then divided by the number of fully diluted shares expected to be outstanding by Ensco management following completion of the merger based on the 1.60x exchange ratio provided for in the merger agreement. This analysis resulted in a range of per Ensco Class A ordinary share values of $19.93 to $23.59 for Ensco Management Case A and $11.17 to $13.84 for Ensco Management Case B. These ranges compared with ranges of implied values per Ensco Class A ordinary share on a standalone basis for each of Ensco Management Case A and Ensco Management Case B of $19.07 to $22.57 and $10.12 to $12.63, respectively.

Illustrative Floater Value Analysis

        Morgan Stanley performed an illustrative floater value analysis of Atwood, which is designed to provide an illustrative value per floater that is implied by the value of the transaction and comparing such value to the replacement cost of a floater (i.e., by building a new rig, called a "newbuild"). Morgan Stanley first calculated the implied transaction value of Atwood based on the 1.60x exchange ratio provided for in the merger agreement. The implied transaction value was calculated using an assumed equity offer price of $10.72 per Atwood share as of May 26, 2017. In order to isolate the implied value of Atwood's floaters, Morgan Stanley then deducted from the implied transaction value an assumed jackup rig value of Atwood (such value was the product of the jackup rig count of Atwood as of March 31, 2017 based on publicly available information multiplied by a per rig value assumption based on public equity research estimates and as reviewed by Ensco management, plus the jackup contract backlog value (which was assumed as 40% of the reported jackup rig backlog value of Atwood as of March 31, 2017 based on publicly available information)). In order to account for construction

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costs associated with the floaters captured in the analysis, Morgan Stanley then added unfunded capital expenditures for certain newbuild floaters. In order to calculate an implied value per floater on an uncontracted basis, Morgan Stanley then deducted the backlog order of floaters (which was assumed as 40% of the reported floater contract backlog value of Atwood as of March 31, 2017), which resulted in an implied floater fleet value of $1,349 million. This value was divided by the number of floaters of Atwood as of March 31, 2017 based on publicly available information (including newbuilds and excluding cold-stacked rigs) to determine the implied purchase price per floater.

        Based on the above-described analysis, Morgan Stanley derived an implied price of $225 million per floater of Atwood and compared it to the estimated cost of constructing a new floater of $600 million, as estimated by Ensco management, which indicated a discount of 63%.

        The illustrative floater value analysis was presented for reference purposes only, and was not relied upon for valuation purposes.

Other Information

Broker Price Targets

        Morgan Stanley reviewed publicly available equity research analysts' 12-month share price targets for Atwood common stock and Ensco Class A ordinary shares. Morgan Stanley noted that the price targets issued by those research analysts with publicly available price targets ranged from $7.00 to $18.00 per share of Atwood common stock and $6.00 to $15.00 per Ensco Class A ordinary share.

        Morgan Stanley then calculated the exchange ratio range implied by the broker price targets. Morgan Stanley compared the lowest research target per share for Atwood common stock to the highest research target per Ensco Class A ordinary share to derive the lowest exchange ratio implied by the broker price targets. Similarly, Morgan Stanley compared the highest research target per share for Atwood common stock to the lowest research target per Ensco Class A ordinary share to derive the highest exchange ratio implied by the broker price targets. The implied exchange ratio reference range resulting from this analysis was 0.47x to 3.00x. Morgan Stanley noted that the merger agreement provided for an exchange ratio of 1.60x.

        The public market trading price targets published by securities research analysts do not necessarily reflect the current market trading prices for shares of Atwood common stock or Ensco Class A ordinary shares, and these estimates are subject to uncertainties, including the future financial performance of Atwood and Ensco as well as future market conditions.

        The analysts' price targets were presented for reference purposes only, and were not relied upon for valuation purposes.

Historical Trading Prices

        Morgan Stanley reviewed the historical trading prices of Atwood common stock and Ensco Class A ordinary shares during the 52-week period ended May 26, 2017, which reflected low to high closing prices for Atwood common stock during such period of $6.12 to $15.37 per share and Ensco Class A ordinary shares of $6.50 to $12.04 per share during such period. Morgan Stanley then calculated the exchange ratio implied by the share price range for Atwood and Ensco during the 52-week period. Morgan Stanley compared the lowest closing price for Atwood common stock to the highest closing price for Ensco Class A ordinary shares to derive the lowest exchange ratio implied by the historical trading prices during the 52-week period ended May 26, 2017. Similarly, Morgan Stanley compared the highest closing per share for Atwood common stock to the lowest closing price per Ensco Class A ordinary share to derive the highest exchange ratio implied by the historical trading prices during the 52-week period ended May 26, 2017. The implied exchange ratio reference range resulting from this

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analysis was 0.51x to 2.37x. Morgan Stanley noted that the merger agreement provided for an exchange ratio of 1.60x.

        The historical trading prices were presented for reference purposes only, and were not relied upon for valuation purposes.

Illustrative Transaction Value Creation Analysis

        Morgan Stanley performed an illustrative transaction value creation analysis, the purpose of which is to review the implied increase in market value to the Ensco shareholders based on assumptions regarding synergies and pro forma ownership of the combined company. The illustrative transaction value creation analysis was performed for illustrative purposes only and is not indicative of actual trading levels and does not take into account the timing to achieve any synergies or the timing of the closing of the transaction.

        In its illustrative analysis, Morgan Stanley first calculated the then-current equity market value of Ensco as of the close of trading on May 26, 2017, which resulted in a value of approximately $2.043 billion. Morgan Stanley then calculated the then-current equity market value of Atwood as of the close of trading on May 26, 2017, which resulted in a value of approximately $0.671 billion. Morgan Stanley then noted that the exchange ratio set forth in the merger agreement of 1.60x implied a pro forma ownership of approximately 30% of the combined company by Atwood shareholders and approximately 70% by Ensco stockholders, using market prices on May 26, 2017, and thus, Atwood shareholders would hypothetically receive approximately 30% of the then-current market value of Ensco and Ensco shareholders would hypothetically receive approximately 70% of the then-current market value of Atwood.

        Morgan Stanley also noted that based on the implied fully-diluted pro forma ownership, Atwood shareholders would hypothetically receive approximately 30% of any increase in market value from synergies in connection with the merger while Ensco shareholders would hypothetically receive approximately 70% of any increase in market value from synergies in connection with the merger. For purposes of this analysis, Morgan Stanley assumed run-rate synergies of $65 million, as directed by Ensco management. The present value of these synergies was calculated by discounting the estimated future cash flows from synergies, net of costs to achieve, to March 31, 2017, using a discount rate of 8.0% for the period between April 1, 2017 through December 31, 2020 based on the midpoint of Morgan Stanley's estimate of Ensco's range of WACC for such period, and a discount rate of 8.2% for the period thereafter based on the midpoint of Morgan Stanley's estimate of Ensco's range for WACC for such period.

        The illustrative analysis indicated the following:

Transaction Value Creation Analysis
  $ in millions  

100% of standalone market value of Ensco as of May 26, 2017

  $ 2,043  

less 30% of standalone market value of Ensco as of May 26, 2017

    (623 )

plus 70% of standalone market value of Atwood as of May 26, 2017

    470  

plus 70% of value of synergies

    366  

Total Value to Ensco Shareholders

  $ 2,255  

        Morgan Stanley noted that the illustrative analysis indicated a value to Ensco shareholders that was approximately $212 million or approximately 10.4% higher than Ensco equity market value as of the close of trading on May 26, 2017.

        The illustrative transaction value creation analysis was presented for reference purposes only, and was not relied upon for valuation purposes.

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General

        In connection with the review of the merger agreement and the transactions contemplated thereby by the Ensco Board, Morgan Stanley performed a variety of financial and comparative analyses for purposes of rendering its opinion. The preparation of a financial opinion is a complex process and is not necessarily susceptible to a partial analysis or summary description. In arriving at its opinion, Morgan Stanley considered the results of all of its analyses as a whole and did not attribute any particular weight to any analysis or factor it considered. However, given that management of Ensco informed Morgan Stanley that Ensco Management Case B was more reflective of the then-current market outlook than Ensco Management Case A, Morgan Stanley used only Ensco Management Case B in certain analyses. Morgan Stanley believes that selecting any portion of its analyses, without considering all analyses as a whole, would create an incomplete view of the process underlying its analyses and opinion. In addition, Morgan Stanley may have given various analyses and factors more or less weight than other analyses and factors, and may have deemed various assumptions more or less probable than other assumptions. As a result, the ranges of valuations resulting from any particular analysis described above should not be taken to be Morgan Stanley's view of the actual value of Atwood or Ensco. In performing its analyses, Morgan Stanley made numerous assumptions with regard to industry performance, general business, economic, market and financial conditions and other matters, many of which are beyond the control of Atwood or Ensco. These include, among other things, the impact of competition on Atwood's and Ensco's businesses and the industry generally, industry growth, and the absence of any adverse material change in the financial condition and prospects of Atwood or Ensco, or the industry, or in the financial markets in general. Any estimates contained in Morgan Stanley's analyses are not necessarily indicative of future results or actual values, which may be significantly more or less favorable than those suggested by such estimates.

        Morgan Stanley conducted the analyses described above solely as part of its analysis of whether the exchange ratio pursuant to the merger agreement was fair from a financial point of view to Ensco and in connection with the delivery of its opinion, dated May 29, 2017, to the Ensco Board. These analyses do not purport to be appraisals or to reflect the prices at which shares of Atwood common stock or Ensco Class A ordinary shares might actually trade.

        The exchange ratio was determined through arm's-length negotiations between Atwood and Ensco and was approved by the Ensco Board. Morgan Stanley provided advice to Ensco during these negotiations. Morgan Stanley did not, however, recommend any specific exchange ratio to Ensco, nor that any specific exchange ratio constituted the only appropriate exchange ratio for the merger. Morgan Stanley's opinion did not address the relative merits of the merger as compared to any other alternative business transaction, or other alternatives, or whether or not such alternatives could be achieved or are available. In addition, Morgan Stanley's opinion was not intended to, and did not, in any manner, address the price at which the Ensco Class A ordinary shares would trade following the merger or at any time, and Morgan Stanley expressed no opinion or recommendation to any holder of Ensco Class A ordinary shares or Atwood common stock as to how such holder should vote at the Ensco general meeting or the Atwood special meeting, respectively, or whether to take any other action with respect to the merger.

        Morgan Stanley's opinion and its oral presentation to the Ensco Board was one of many factors taken into consideration by the Ensco Board in deciding to approve the merger agreement and the transactions contemplated thereby. Consequently, the analyses as described above should not be viewed as determinative of the opinion of the Ensco Board with respect to the exchange ratio pursuant to the merger agreement or of whether the Ensco Board would have been willing to agree to a different exchange ratio.

        Morgan Stanley's opinion was approved by a committee of Morgan Stanley investment banking and other professionals in accordance with Morgan Stanley's customary practice. Morgan Stanley is a

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global financial services firm engaged in the securities, investment management and individual wealth management businesses. Its securities business is engaged in securities underwriting, trading and brokerage activities, foreign exchange, commodities and derivatives trading, prime brokerage, as well as providing investment banking, financing and financial advisory services. Morgan Stanley, its affiliates, directors and officers may at any time invest on a principal basis or manage funds that invest, hold long or short positions, finance positions, and may trade or otherwise structure and effect transactions, for its own account or the accounts of its customers, in debt or equity securities or loans of Ensco, Atwood or any other company, or any currency or commodity, that may be involved in the merger, or any related derivative instrument.

        Under the terms of its engagement letter, Morgan Stanley provided the Ensco Board with financial advisory services and a financial opinion described in this section and attached as Annex B to this joint proxy statement/prospectus in connection with the merger, and Ensco has agreed to pay Morgan Stanley a fee, upon rendering its fairness opinion, of $2 million payable upon the earlier of the closing of the merger or the termination of the merger agreement. If the merger is concluded, Ensco has agreed to pay Morgan Stanley a transaction fee of $8 million (less any fee that has been previously paid), which is payable upon and is contingent upon the consummation of the merger. Ensco has also agreed to reimburse Morgan Stanley for its expenses incurred in performing its services. In addition, Ensco has agreed to indemnify Morgan Stanley and its affiliates, their respective officers, directors, employees and agents and each person, if any, controlling Morgan Stanley or any of its affiliates against certain liabilities and expenses, including certain liabilities under the federal securities laws, relating to or arising out of Morgan Stanley's engagement. Ensco also retained DNB Capital LLC and HSBC Securities (USA) Inc. as co-financial advisors to provide financial advisory services to Ensco's management related to the potential transaction with Atwood and to assist in structuring the combined company's anticipated capitalization following the merger and agreed to pay each such advisor $2.5 million upon the consummation of the merger.

        In the two years prior to the date of Morgan Stanley's opinion, in addition to the services provided in connection with the merger and the opinion, Morgan Stanley provided financial advisory and financing services to Ensco and its affiliates and received aggregate fees of between $4 million and $5 million in connection with such services. Morgan Stanley is also a lender under Ensco's revolving credit facility. During the same period, Morgan Stanley did not provide any financial advisory or financing services to Atwood or its affiliates, and did not receive any fees for financial advisory or financing services from Atwood or its affiliates. Morgan Stanley previously met with Atwood in March 2017 to review a broad array of potential strategic alternatives for Atwood which included potential financing and M&A transactions. The materials prepared by Morgan Stanley for such meetings were based solely on publicly available information and included analysis of an illustrative combination of Atwood with a number of other potential parties, including Ensco. Morgan Stanley may seek to provide financial advisory and financing services to Atwood, Ensco and their respective affiliates in the future and would expect to receive fees for the rendering of those services.

Opinion of Financial Advisor to Atwood

        Goldman Sachs rendered its opinion to the Atwood Board that, as of May 29, 2017 and based upon and subject to the factors and assumptions set forth therein, the exchange ratio pursuant to the merger agreement was fair from a financial point of view to the holders (other than Ensco and its affiliates) of shares of Atwood common stock.

        The full text of the written opinion of Goldman Sachs, dated May 29, 2017, which sets forth assumptions made, procedures followed, matters considered and limitations on the review undertaken in connection with the opinion, is attached as Annex C to this joint proxy statement/prospectus. Goldman Sachs provided its opinion for the information and assistance of the Atwood Board in connection with its consideration of the transaction. The Goldman Sachs opinion is not a

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recommendation as to how any holder of shares of Atwood common stock should vote with respect to the transaction or any other matter.

        In connection with rendering the opinion described above and performing its related financial analyses, Goldman Sachs reviewed, among other things:

        Goldman Sachs also held discussions with members of the senior management of Atwood regarding their assessment of the strategic rationale for, and the potential benefits of, the transaction and the past and current business operations, financial condition, and future prospects of Atwood and with members of the senior managements of Atwood and Ensco regarding their assessment of the past and current business operations, financial condition and future prospects of Ensco; reviewed the reported price and trading activity for the shares of Atwood common stock and the Ensco Class A ordinary shares; compared certain financial and stock market information for Atwood and Ensco with similar information for certain other companies the securities of which are publicly traded; and performed such other studies and analyses, and considered such other factors, as it deemed appropriate.

        For purposes of rendering this opinion, Goldman Sachs, with Atwood's consent, relied upon and assumed the accuracy and completeness of all of the financial, legal, regulatory, tax, accounting and other information provided to, discussed with or reviewed by, it, without assuming any responsibility for independent verification thereof. In that regard, Goldman Sachs assumed with Atwood's consent that the Forecasts, including the Atwood Synergies were reasonably prepared on a basis reflecting the best currently available estimates and judgments of the management of Atwood. Goldman Sachs did not make an independent evaluation or appraisal of the assets and liabilities (including any contingent, derivative or other off-balance-sheet assets and liabilities) of Atwood or Ensco or any of their respective subsidiaries and it was not furnished with any such evaluation or appraisal. Goldman Sachs was not requested to solicit, and did not solicit, interest from other parties with respect to an acquisition of, or other business combination with, Atwood or any alternative transaction. Goldman Sachs assumed that all governmental, regulatory or other consents and approvals necessary for the consummation of the merger will be obtained without any adverse effect on Atwood or Ensco or on the expected benefits of the transaction in any way meaningful to its analysis. Goldman Sachs has also assumed that the transaction will be consummated on the terms set forth in the merger agreement, without the waiver or modification of any term or condition the effect of which would be in any way meaningful to its analysis.

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        Goldman Sachs' opinion does not address the underlying business decision of Atwood to engage in the transaction or the relative merits of the transaction as compared to any strategic alternatives that may be available to Atwood; nor does it address any legal, regulatory, tax or accounting matters. Goldman Sachs' opinion addresses only the fairness from a financial point of view to holders of shares of Atwood common stock (other than Ensco and its affiliates), as of the date of the opinion, of the exchange ratio pursuant to the merger agreement. Goldman Sachs' opinion does not express any view on, and does not address, any other term or aspect of the merger agreement or the transaction or any term or aspect of any other agreement or instrument contemplated by the merger agreement or entered into or amended in connection with the transaction, including the fairness of the transaction to, or any consideration received in connection therewith by, the holders of any other class of securities, creditors, or other constituencies of Atwood; nor as to the fairness of the amount or nature of any compensation to be paid or payable to any of the officers, directors or employees of Atwood or Ensco, or class of such persons, in connection with the transaction, whether relative to the exchange ratio pursuant to the merger agreement or otherwise. Goldman Sachs' opinion was necessarily based on economic, monetary, market and other conditions as in effect on, and the information made available to it as of, the date of the opinion and Goldman Sachs assumed no responsibility for updating, revising or reaffirming its opinion based on circumstances, developments or events occurring after the date of its opinion. In addition, Goldman Sachs does not express any opinion as to the prices at which Ensco Class A ordinary shares will trade at any time or as to the impact of the transaction on the solvency or viability of Atwood or Ensco or the ability of Atwood or Ensco to pay their respective obligations when they come due. Goldman Sachs' opinion was approved by a fairness committee of Goldman Sachs.

        The following is a summary of the material financial analyses delivered by Goldman Sachs to the Atwood Board in connection with rendering the opinion described above. The following summary, however, does not purport to be a complete description of the financial analyses performed by Goldman Sachs, nor does the order of analyses described represent relative importance or weight given to those analyses by Goldman Sachs. Some of the summaries of the financial analyses include information presented in tabular format. The tables must be read together with the full text of each summary and are alone not a complete description of Goldman Sachs' financial analyses. Except as otherwise noted, the following quantitative information, to the extent that it is based on market data, is based on market data as it existed on or before May 26, 2017 (the last trading day prior to public announcement of the transaction), and is not necessarily indicative of current market conditions.

        Historical Stock Trading Analysis.    Goldman Sachs analyzed the implied deal price of $10.72 per share to be paid to holders (other than Ensco and its affiliates) of shares of Atwood common stock pursuant to the merger agreement based on the exchange ratio of 1.60x and the closing market price of Ensco Class A ordinary shares on May 26, 2017, in relation to the closing market price of shares of Atwood common stock on May 26, 2017 (the last trading day prior to public announcement of the transaction), the volume-weighted average closing prices of shares of Atwood common stock for the 30-day, 60-day and 90-day periods ended May 26, 2017, and the 52-week high and low market prices of shares of Atwood common stock for the period ended May 26, 2017. Goldman Sachs calculated the exchange ratios by dividing the value per share of Atwood common stock by the value per Ensco Class A ordinary share using the closing market prices on May 26, 2017 (the last trading day prior to public announcement of the transaction), and calculated the average exchange ratios for the 30-trading day, 60-trading day, and 90-trading day periods ended May 26, 2017, and the 365-trading day high and low exchange ratio for the period ended May 26, 2017. This analysis indicated that the implied deal price per share to be paid to holders (other than Ensco and its affiliates) of shares of Atwood common stock pursuant to the merger agreement represented:

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        Implied Multiples Analysis.    Goldman Sachs calculated various financial multiples and ratios for Atwood using the implied deal price of $10.72 per share to be paid to holders (other than Ensco and its affiliates) of shares of Atwood common stock pursuant to the merger agreement based on the exchange ratio of 1.60x and the closing market price of Ensco Class A ordinary shares on May 26, 2017, the median estimates from Institutional Brokers' Estimate System (referred to herein as "IBES") for Atwood, and the Atwood Forecasts.

        In particular, Goldman Sachs calculated the enterprise value (referred to herein as "EV") of Atwood, which is the market capitalization of Atwood based on the implied deal price of $10.72, multiplied by the number of fully diluted shares of Atwood common stock outstanding as of May 26, 2017, as provided by the management of Atwood, plus the total debt amount, less cash and equivalents as of March 31, 2017, as obtained from Atwood's public filings, as a multiple of estimated earnings before interest, taxes, depreciation and amortization (referred to herein as "EBITDA") for calendar years 2017, 2018 and 2019, respectively.

        The following table presents the results of these analyses:

Ratio of Equivalent Value to Estimated EBITDA
  IBES   Management  

EV / 2017E EBITDA

    10.1x     9.8x  

EV / 2018E EBITDA

    46.2     NM  

EV / 2019E EBITDA

    17.4     15.2  

        Selected Companies Analysis.    Goldman Sachs reviewed and compared certain financial information for Atwood and Ensco to corresponding financial information, ratios and public market multiples for the following publicly traded corporations in the offshore drilling industry (collectively referred to as the "Selected Companies"):

        Although none of the Selected Companies are directly comparable to Atwood or Ensco, the companies included were selected because they are publicly traded companies with operations that for purposes of analysis may be considered similar to certain operations of Atwood and Ensco.

        Goldman Sachs calculated and compared various financial multiples and ratios for the Selected Companies, Atwood and Ensco. The financial multiples and ratios for the Selected Companies were based on closing stock market prices on May 26, 2017, information obtained from public filings, Bloomberg and Capital IQ, and estimates from IBES. The financial multiples and ratios for Atwood

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and Ensco were based on closing stock market prices on May 26, 2017, information obtained from public filings, Bloomberg and Capital IQ and the number of fully diluted shares of Atwood common stock and Ensco Class A ordinary shares outstanding as of May 26, 2017, as provided by the management of Atwood.

        With respect to each of the Selected Companies, Atwood and Ensco, Goldman Sachs calculated the ratios of EV as of May 26, 2017 to each estimated calendar year 2017 to 2019 EBITDA, which is referred to below as "EV/EBITDA".

        The results of this analysis are shown in the table below.

 
  EV/EBITDA  
Company
  2017E   2018E   2019E  

Atwood

    8.9x     40.4x     15.2x  

Ensco

    7.9     10.0     9.1  

Transocean Ltd. 

    7.2     9.3     9.1  

Diamond Offshore Drilling, Inc. 

    6.0     7.5     8.2  

Rowan Companies plc

    7.1     14.3     15.2  

Noble Corporation plc

    10.9     12.2     11.4  

Seadrill Limited

    10.1     15.5     13.1  

Median

    7.5x     11.1x     10.3x  

        Historical Exchange Ratio Analysis.    Goldman Sachs calculated the average historical exchange ratios of shares of Atwood common stock to Ensco Class A ordinary shares based on the closing prices of shares of Atwood common stock and Ensco Class A ordinary shares since Atwood's equity offering on January 9, 2017, during the 30-trading day, 60-trading day, 90-trading day, six-month, one-year, three-year and five-year periods ended May 26, 2017, and on May 26, 2017. Goldman Sachs also calculated for each period the implied premium to be paid to holders (other than Ensco and its affiliates) of shares of Atwood common stock pursuant to the merger agreement based on the exchange ratio of 1.60x. The following table presents the results of this analysis:

Time Period (up to May 26, 2017)
  Implied Exchange Ratio of Atwood
common stock to Ensco Class A
ordinary shares
  Implied Offer (1.60x)
Premium
 

May 26, 2017

    1.21     33 %

Since Atwood's Equity Offering on January 9, 2017

    1.07     50 %

30-day Average

    1.04     54 %

60-day Average

    1.04     53 %

90-day Average

    1.05     52 %

6-month Average

    1.10     45 %

1-year Average

    1.09     46 %

3-year Average

    1.04     54 %

5-year Average

    0.98     63 %

Illustrative Discounted Cash Flow Analysis—5-year DCF Model.

Atwood Standalone

        Using the Atwood Forecasts for the calendar years 2017 to 2021, Goldman Sachs performed a five-year illustrative discounted cash flow analysis on Atwood on a standalone basis to generate ranges for the implied present value per share of Atwood common stock. Using discount rates ranging from 13.0% to 15.0%, reflecting estimates of Atwood's weighted average cost of capital, and assuming mid-year convention, Goldman Sachs discounted to present value as of March 31, 2017 (i) estimates of

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Atwood's unlevered free cash flows for the period April 1, 2017 to December 31, 2021 and (ii) a range of illustrative terminal values for Atwood, which were calculated by applying EV/EBITDA multiples ranging from 5.5x to 7.5x to a terminal year estimate of EBITDA to be generated by Atwood, as reflected in the Atwood Forecasts. The range of EBITDA multiples were estimated by Goldman Sachs based on the EV/EBITDA multiples of the Selected Companies analyzed for the purposes of the "Selected Companies Analysis" described above taking into account current and historical trading data and the current and historical enterprise value to forward year EBITDA multiples for Atwood, Ensco and the Selected Companies. Goldman Sachs derived ranges of illustrative enterprise values for Atwood by adding the ranges of present values it derived above. Goldman Sachs then subtracted Atwood's net debt, as obtained from public filings, from the range of illustrative enterprise values it derived to determine a range of illustrative equity values for Atwood. Goldman Sachs then calculated the illustrative range of present values per share of Atwood common stock by dividing the range of illustrative equity values by the number of fully diluted outstanding shares of Atwood provided by the management of Atwood. This analysis indicated an illustrative range of present values of $4.67 to $11.46 per share of Atwood common stock.

Ensco Standalone

        Using the Atwood Forecasts for Ensco for the calendar years 2017 to 2021, Goldman Sachs performed a five-year illustrative discounted cash flow analysis on Ensco on a standalone basis to generate ranges for the implied present value per Ensco Class A ordinary share. Using discount rates ranging from 12.0% to 14.0%, reflecting estimates of Ensco's weighted average cost of capital, and assuming mid-year convention, Goldman Sachs discounted to present value as of March 31, 2017 (i) estimates of Ensco's unlevered free cash flows for the period April 1, 2017 to December 31, 2021 and (ii) a range of illustrative terminal values for Ensco, which were calculated by applying EV/EBITDA multiples ranging from 5.5x to 7.5x to a terminal year estimate of EBITDA to be generated by Ensco, as reflected in the Atwood Forecasts for Ensco. The range of EBITDA multiples were estimated by Goldman Sachs based on the EV/EBITDA multiples of the Selected Companies analyzed for the purposes of the "Selected Companies Analysis" described above taking into account current and historical trading data and the current and historical enterprise value to forward year EBITDA multiples for Atwood, Ensco and the Selected Companies. Goldman Sachs derived ranges of illustrative enterprise values for Ensco by adding the ranges of present values it derived above. Goldman Sachs then subtracted Ensco's net debt, as provided by Ensco management and provided to Goldman Sachs by the management of Atwood, from the range of illustrative enterprise values it derived to determine a range of illustrative equity values for Ensco. Goldman Sachs then calculated the illustrative range of present values per Ensco Class A ordinary share by dividing the range of illustrative equity values by the number of fully diluted outstanding shares of Ensco provided by the management of Atwood. This analysis indicated an illustrative range of present values of $3.79 to $8.30 per Ensco Class A ordinary share.

Pro Forma

        Using the Atwood Forecasts and Atwood Forecasts for Ensco for the calendar years 2017 to 2021, respectively, and Atwood Synergies, Goldman Sachs generated reference ranges for the implied value per ordinary share of the combined company.

        Using discount rates ranging from 12.0% to 14.0%, reflecting estimates of the pro forma weighted average cost of capital of the combined company, and assuming mid-year convention, Goldman Sachs discounted to present value as of March 31, 2017 (i) estimates of the combined company's unlevered free cash flows for the period April 1, 2017 to December 31, 2021 and (ii) a range of illustrative terminal values for the combined company, which were calculated by applying EV/EBITDA multiples ranging from 5.5x to 7.5x to a terminal year estimate of EBITDA to be generated by the combined

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company, calculated using the Atwood Forecasts, Atwood Forecasts for Ensco and Atwood Synergies. Goldman Sachs derived ranges of illustrative enterprise values for the combined company by adding the ranges of present values it derived above. Goldman Sachs then subtracted the combined company's pro forma net debt, as provided by the management of Atwood, from the range of illustrative enterprise values it derived to determine a range of illustrative equity values for the combined company. Goldman Sachs then calculated the illustrative range of present values per ordinary share of the combined company by dividing the range of illustrative equity values by the number of estimated pro forma fully diluted outstanding shares of the combined company following closing, as provided by the management of Atwood. This analysis indicated an illustrative range of present values of $5.54 to $12.72 per ordinary share of the combined company.

Illustrative Discounted Cash Flow Analysis—Asset Life Model.

Atwood Standalone

        Using the Atwood Forecasts, Goldman Sachs calculated the present value of the unlevered free cash flows that Atwood could be expected to generate from its existing assets as of March 31, 2017 for their estimated remaining lives. Goldman Sachs calculated net present values of the unlevered free cash flows using discount rates ranging from 13.0% to 15.0%, reflecting estimates of the weighted average cost of capital of Atwood. Goldman Sachs derived a range of illustrative enterprise values for Atwood by adding the ranges of present values it derived above. Goldman Sachs then subtracted Atwood's net debt, as obtained from public filings, from the range of illustrative enterprise values it derived to determine a range of illustrative equity values for Atwood. Goldman Sachs then calculated the illustrative range of present values per share of Atwood common stock by dividing the range of illustrative equity values for Atwood by the number of fully diluted outstanding shares of Atwood provided by the management of Atwood. This analysis implied an illustrative range of net asset values of $4.46 to $7.24 per share of Atwood common stock.

Ensco Standalone

        Using the Atwood Forecasts for Ensco, Goldman Sachs calculated the present value of the unlevered free cash flows that Ensco could be expected to generate from its existing assets as of March 31, 2017 for their estimated remaining lives. Goldman Sachs calculated net present values of the unlevered free cash flows for Ensco using discount rates ranging from 12.0% to 14.0%, reflecting estimates of the weighted average cost of capital of Ensco. Goldman Sachs derived a range of illustrative enterprise values for Ensco by adding the ranges of present values it derived above. Goldman Sachs then subtracted Ensco's net debt, as provided by Ensco management and provided to Goldman Sachs by the management of Atwood, from the range of illustrative enterprise values it derived to determine a range of illustrative equity values for Ensco. Goldman Sachs then calculated the illustrative range of present values per Ensco Class A ordinary share by dividing the range of illustrative equity values for Ensco by the number of fully diluted outstanding ordinary shares of Ensco provided by the management of Atwood. This analysis implied an illustrative range of net asset values of $4.05 to $6.02 per Ensco Class A ordinary share.

Pro Forma

        Using the Atwood Forecasts, Atwood Forecasts for Ensco and Atwood Synergies, Goldman Sachs calculated the present value of the unlevered free cash flows that the combined company could be expected to generate from the combined company's pro forma assets existing as of March 31, 2017 for their estimated remaining lives. Goldman Sachs calculated net present values of the unlevered free cash flows for the combined company using discount rates ranging from 12.0% to 14.0%, reflecting estimates of the weighted average cost of capital of the combined company. Goldman Sachs derived a range of illustrative enterprise values for the combined company by adding the ranges of present values it

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derived above. Goldman Sachs then subtracted the combined company's pro forma net debt, as provided by the management of Atwood, from the range of illustrative enterprise values it derived to determine a range of illustrative equity values. Goldman Sachs then calculated the illustrative range of present values per ordinary share of the combined company by dividing the range of illustrative equity values for the combined company by the number of pro forma fully diluted outstanding shares provided by the management of Atwood. This analysis implied an illustrative range of net asset values of $5.99 to $9.14 per share of the combined company.

Relative Discounted Cash Flow Analysis

Five-year DCF Model

        Goldman Sachs performed an illustrative relative discounted cash flow analysis based on the results of its five-year discounted cash flow analyses on Atwood and Ensco on a standalone basis to determine the implied exchange ratio of shares of Atwood common stock to Ensco Class A ordinary shares. Goldman Sachs calculated the implied exchange ratio by dividing the illustrative range of present values per share of Atwood common stock from its five-year illustrative discounted cash flow analysis on Atwood on a standalone basis by the illustrative range of present values per Ensco Class A ordinary share from its five-year illustrative discounted cash flow analysis on Ensco on a standalone basis. This analysis resulted in a range of implied exchange ratios of 1.234x to 1.381x.

Asset Life Model

        Goldman Sachs performed an illustrative relative discounted cash flow analysis based on the results of its Asset Life Model discounted cash flow analyses on Atwood and Ensco on a standalone basis to determine the implied exchange ratio of shares of Atwood common stock to Ensco Class A ordinary shares. Goldman Sachs calculated the implied exchange ratio by dividing the illustrative range of net asset values per share of Atwood common stock from its Asset Life Model discounted cash flow analysis on Atwood on a standalone basis by the illustrative range of net asset values per Ensco Class A ordinary share from its Asset Life Model discounted cash flow analysis on Ensco on a standalone basis. This analysis resulted in a range of implied exchange ratios of 1.100x to 1.203x.

        The preparation of a fairness opinion is a complex process and is not necessarily susceptible to partial analysis or summary description. Selecting portions of the analyses or of the summary set forth above, without considering the analyses as a whole, could create an incomplete view of the processes underlying Goldman Sachs' opinion. In arriving at its fairness determination, Goldman Sachs considered the results of all of its analyses and did not attribute any particular weight to any factor or analysis considered by it. Rather, Goldman Sachs made its determination as to fairness on the basis of its experience and professional judgment after considering the results of all of its analyses. No company or transaction used in the above analyses as a comparison is directly comparable to Atwood or Ensco or the contemplated transaction.

        Goldman Sachs prepared these analyses for purposes of Goldman Sachs' providing its opinion to the Atwood Board as to the fairness of the exchange ratio pursuant to the merger agreement from a financial point of view to the holders (other than Ensco and its affiliates) of shares of Atwood common stock. These analyses do not purport to be appraisals nor do they necessarily reflect the prices at which businesses or securities actually may be sold. Analyses based upon forecasts of future results are not necessarily indicative of actual future results, which may be significantly more or less favorable than suggested by these analyses. Because these analyses are inherently subject to uncertainty, being based upon numerous factors or events beyond the control of the parties or their respective advisors, none of Atwood, Ensco, Goldman Sachs or any other person assumes responsibility if future results are materially different from those forecast.

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        The exchange ratio was determined through arm's-length negotiations between Atwood and Ensco and was approved by the Atwood Board. Goldman Sachs provided advice to Atwood during these negotiations. Goldman Sachs did not, however, recommend any specific exchange ratio to Atwood or the Atwood Board or that any specific exchange ratio constituted the only appropriate exchange ratio for the transaction.

        As described above, Goldman Sachs' opinion to the Atwood Board was one of many factors taken into consideration by the Atwood Board in making its determination to approve the merger agreement. The foregoing summary does not purport to be a complete description of the analyses performed by Goldman Sachs in connection with the fairness opinion and is qualified in its entirety by reference to the written opinion of Goldman Sachs attached as Annex C to this joint proxy statement/prospectus.

        Goldman Sachs and its affiliates are engaged in advisory, underwriting and financing, principal investing, sales and trading, research, investment management and other financial and non-financial activities and services for various persons and entities. Goldman Sachs and its affiliates and employees, and funds or other entities in which they invest or with which they co-invest, may at any time purchase, sell, hold or vote long or short positions and investments in securities, derivatives, loans, commodities, currencies, credit default swaps and other financial instruments of Atwood, Ensco, any of their respective affiliates and third parties, or any currency or commodity that may be involved in the transaction contemplated by the merger agreement for the accounts of Goldman Sachs and its affiliates and employees and their customers. Goldman Sachs acted as financial advisor to Atwood in connection with, and participated in certain of the negotiations leading to, the transaction contemplated by the agreement. Goldman Sachs has provided certain financial advisory and/or underwriting services to Atwood and its affiliates from time to time for which the Investment Banking Division of Goldman Sachs has received, and may receive, compensation, including having acted as lead bookrunner in connection with the public offering of 15,525,000 shares of Atwood common stock in January 2017. Goldman Sachs also has provided certain financial advisory and/or underwriting services to Ensco and its affiliates from time to time for which the Investment Banking Division of Goldman Sachs has received, and may receive, compensation, including having acted as lead bookrunner in connection with the public offering of 57,000,000 Ensco Class A ordinary shares in April 2016 and dealer manager in connection with a tender offer by Ensco for its 8.50% Senior Notes due 2019, 4.70% Senior Notes due 2021, 6.875% Senior Notes due 2020, 4.50% Senior Notes due 2024 and 5.20% Senior Notes due 2025 (aggregate principal amount $750 million) in April 2016. Goldman Sachs may also in the future provide investment banking services to Atwood, Ensco and their respective affiliates for which the Investment Banking Division of Goldman Sachs may receive compensation. During the two year period ended May 29, 2017, Goldman Sachs has received compensation for financial advisory and/or underwriting services provided by its Investment Banking Division to Atwood and/or its affiliates and Ensco and/or its affiliates of approximately $5.0 million and approximately $4.5 million, respectively.

        The Atwood Board selected Goldman Sachs as its financial advisor because it is an internationally recognized investment banking firm that has substantial experience in transactions similar to the transaction. Pursuant to a letter agreement dated May 26, 2017, Atwood engaged Goldman Sachs to act as its financial advisor in connection with the contemplated transaction. The engagement letter between Atwood and Goldman Sachs provides for a transaction fee that is estimated, based on the information available as of the date of announcement of the transaction, at approximately $21 million, $3 million of which became payable upon execution of the merger agreement, and the remainder of which is contingent upon consummation of the merger. In addition, Atwood has agreed to reimburse Goldman Sachs for certain of its expenses, including attorneys' fees and disbursements, and to indemnify Goldman Sachs and related persons against various liabilities, including certain liabilities under the federal securities laws.

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Certain Unaudited Financial Forecasts Prepared by the Management of Ensco

        For internal planning purposes and in connection with the proposed merger, Ensco's management prepared forecasts of expected future financial and operating performance of Ensco and of Atwood (the "Ensco financial forecasts" and "Atwood financial forecasts," respectively). These forecasts were for multiple years and consisted of two cases, Ensco Management Case A and Ensco Management Case B, with Ensco Management Case B being more reflective of the then-current market outlook than Ensco Management Case A. Select material line items for certain periods from the Ensco financial forecasts and the Atwood financial forecasts, as well as material operating assumptions underlying such forecasts, are set forth below.

        The primary market assumptions underlying the discounted cash flow analysis for each of Ensco Management Case A and Ensco Management Case B included the anticipated period during which utilization and day rates associated with Ensco's/Atwood's jackup rigs and floaters would improve. For Ensco Management Case A, Ensco assumed (i) with respect to Ensco's/Atwood's jackup rigs, utilization recovery beginning in 2017 followed by day rate recovery in 2018, and (ii) with respect to Ensco's/Atwood's floaters, utilization recovery beginning in 2018 followed by day rate recovery in 2019. For Ensco Management Case B, Ensco assumed (i) with respect to Ensco's/Atwood's jackup rigs, utilization recovery beginning in 2018 followed by day rate recovery in 2019, and (ii) with respect to Ensco's/Atwood's floaters, utilization recovery beginning in 2019 followed by day rate recovery in 2020. Ensco Management Case A also included a post-recovery day rate assumption that is 10-15% higher than Ensco Management Case B for both jackup rigs and floaters.

        The Ensco financial forecasts and the Atwood financial forecasts were necessarily based on a variety of assumptions and estimates. The assumptions and estimates underlying such forecasts may not be realized and are inherently subject to significant business, economic and competitive uncertainties and contingencies, all of which are difficult to predict and many of which are beyond Ensco's and Atwood's control. The assumptions and estimates used to create the Ensco financial forecasts and the Atwood financial forecasts involve judgments made with respect to, among other things, growth of revenue, drilling activity in the oil and gas sector, future supply, demand and prices of commodities including crude oil and natural gas, general domestic and foreign economic, regulatory and political conditions, levels of operating expenses and matters specific to the businesses of Ensco and Atwood, all of which are difficult to predict and many of which are outside of Ensco's and Atwood's control. The Ensco financial forecasts and the Atwood financial forecasts also reflect assumptions as to certain business decisions that are subject to change and that do not reflect any of the effects of the merger, or any other changes that may in the future affect Ensco, Atwood or their assets, business, operations, properties, policies, corporate structure, capitalization and management as a result of the merger or otherwise.

        The inclusion of the Ensco financial forecasts and the Atwood financial forecasts in this joint proxy statement/prospectus should not be regarded as an indication that Ensco or any of its advisors or representatives considered or consider such forecasts to be an accurate prediction of future events or that such forecasts will be achieved, and the Ensco financial forecasts and the Atwood financial forecasts should not be relied upon as such. None of Ensco, Atwood or their respective advisors or representatives has made or makes any representation regarding the information contained in the Ensco financial forecasts or the Atwood financial forecasts, and, except as may be required of Ensco or of Atwood by applicable securities laws, none of them intends to update or otherwise revise or reconcile such forecasts to reflect circumstances existing after the date they were generated or to reflect the occurrence of future events even in the event that any or all of the assumptions underlying the Ensco financial forecasts or the Atwood financial forecasts are shown to be in error.

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        Ensco and Atwood shareholders are cautioned not to place undue reliance on the Ensco financial forecasts and the Atwood financial forecasts included in this joint proxy statement/prospectus, and such projected financial information should not be regarded as an indication that Ensco, the Ensco Board or any other person considered, or now considers, them to be reliable predictions of future results, and they should not be relied upon as such.

        Although presented with numerical specificity, the Ensco financial forecasts and the Atwood financial forecasts are not fact and reflect numerous assumptions, estimates and judgments as to future events and the probability of such events made by Ensco's management, including the assumptions, estimates and judgments noted below. Since the Ensco financial forecasts and the Atwood financial forecasts cover multiple years, such information by its nature becomes less predictive with each successive year. There can be no assurance that the assumptions, estimates and judgments used to prepare the Ensco financial forecasts and the Atwood financial forecasts will prove to be accurate, and actual results may differ materially from those contained in such forecasts. The Ensco financial forecasts and the Atwood financial forecasts are forward-looking statements. Please see "Cautionary Statement Regarding Forward-Looking Statements."

        The Ensco financial forecasts and the Atwood financial forecasts included in this joint proxy statement/prospectus have been prepared by, and are the responsibility of, Ensco's management. Neither KPMG LLP, Ensco's independent registered public accounting firm, nor PricewaterhouseCoopers LLP, Atwood's independent registered public accounting firm, has examined, compiled or performed any procedures with respect to the Ensco financial forecasts or the Atwood financial forecasts and, accordingly, KPMG LLP and PricewaterhouseCoopers LLP do not express an opinion or any other form of assurance with respect thereto. The report of KPMG LLP and PricewaterhouseCoopers LLP incorporated by reference in this joint proxy statement/prospectus relate to Ensco's and Atwood's historical financial information, respectively. The foregoing report does not extend to the Ensco financial forecasts or the Atwood financial forecasts and should not be read to do so.

        In addition to being used by the Ensco Board in connection with its deliberations regarding the merger, the Ensco and Atwood financial forecasts were provided to Morgan Stanley. The Ensco financial forecasts for only the years ending December 31, 2017, 2018 and 2019 were provided to Goldman Sachs and Atwood. The Ensco financial forecasts were prepared for use only by the Ensco Board, Ensco, Morgan Stanley and, with respect to the Ensco financial forecasts for the years ending December 31, 2017, 2018 and 2019, Atwood and Goldman Sachs. The Atwood financial forecasts were prepared for use only by the Ensco Board, Ensco and Morgan Stanley.

Summary of Ensco Financial Forecasts and Atwood Financial Forecasts

        The Ensco financial forecasts and Atwood financial forecasts include projected information at the individual rig level and consolidated financial projections through the remaining useful life of the existing Ensco and Atwood fleets (through 2050 and 2055, respectively). However, Ensco believes that operating assumptions beyond a six-year period (beyond 2022) may not be meaningful to current and potential shareholders because such information becomes less predictive with each successive year. As a result, Ensco did not develop discrete operating assumptions beyond a six-year period, and the tables below present summaries of select material line items and material operating assumptions with respect to (a) in the case of the Ensco financial forecasts, each fiscal year during the period from 2017 through 2022 and the fiscal years from 2023 through 2050 in the aggregate and (b) in the case of the Atwood financial forecasts, the nine months ending December 31, 2017, each fiscal year during the period from 2018 through 2022 and the fiscal years from 2023 through 2055 in the aggregate.

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Ensco Management Case A

 
Ensco Financial Forecasts
($ in millions, except Average Dayrate)
2017 2018 2019 2020 2021 2022 2023 - 2050
Total(1)

Revenue

$ 1,930 $ 2,135 $ 2,259 $ 2,483 $ 2,750 $ 2,834 $ 50,450

Contract Drilling Expense

1,210 1,404 1,479 1,454 1,422 1,266 20,856

EBITDA(2)

537 512 589 884 1,210 1,465 28,134

Capital Expenditures

679 297 163 198 159 275 2,992

Unlevered Free Cash Flow(3)

(201 ) 184 370 553 867 981 22,735

Assumptions


 

 

 

 

 

 

 

Average Dayrate

$ 145,800 $ 126,288 $ 138,226 $ 159,951 $ 181,710 $ 221,069 $ 274,895

Utilization

66 % 82 % 85 % 89 % 89 % 86 % 88 %

 

 
Atwood Financial Forecasts
($ in millions, except Average Dayrate)
2017(4) 2018 2019 2020 2021 2022 2023 - 2055
Total(5)

Revenue

$ 320 $ 384 $ 464 $ 677 $ 850 $ 1,014 $ 24,997

Contract Drilling Expense

250 319 337 398 413 412 10,096

EBITDA(2)

31 13 75 227 385 550 13,609

Capital Expenditures(6)

32 41 29 47 52 328 1,382

Unlevered Free Cash Flow(3)

(6 ) (38 ) 34 162 300 178 11,059

Assumptions


 

 

 

 

 

 

 

Average Dayrate

$ 201,343 $ 133,233 $ 154,853 $ 194,568 $ 233,864 $ 280,909 $ 313,191

Utilization

67 % 86 % 89 % 90 % 90 % 89 % 89 %


Ensco Management Case B

 
Ensco Financial Forecasts
($ in millions, except Average Dayrate)
2017 2018 2019 2020 2021 2022 2023 - 2050
Total(1)

Revenue

$ 1,844 $ 1,863 $ 1,872 $ 2,041 $ 2,308 $ 2,483 $ 43,860

Contract Drilling Expense

1,144 1,258 1,360 1,411 1,435 1,279 20,976

EBITDA(2)

511 389 318 485 756 1,099 21,372

Capital Expenditures

660 305 153 191 157 197 3,082

Unlevered Free Cash Flow(3)

(196 ) 92 164 223 479 735 16,515

Assumptions


 

 

 

 

 

 

 

Average Dayrate

$ 152,810 $ 123,572 $ 123,459 $ 139,277 $ 157,183 $ 194,819 $ 242,464

Utilization

58 % 72 % 79 % 85 % 88 % 87 % 86 %
 
Atwood Financial Forecasts
($ in millions, except Average Dayrate)
2017(4) 2018 2019 2020 2021 2022 2023 - 2055
Total(5)

Revenue

$ 276 $ 331 $ 373 $ 555 $ 704 $ 881 $ 21,793

Contract Drilling Expense

215 326 337 398 413 410 10,096

EBITDA(2)

22 (47 ) (16 ) 105 238 419 10,405

Capital Expenditures(6)

32 40 29 47 52 343 1,367

Unlevered Free Cash Flow(3)

(13 ) (98 ) (56 ) 41 162 42 8,219

Assumptions


 

 

 

 

 

 

 

Average Dayrate

$ 269,421 $ 129,888 $ 129,388 $ 161,750 $ 196,818 $ 249,545 $ 276,557

Utilization

43 % 75 % 87 % 89 % 89 % 87 % 88 %

(1)
For any Ensco drilling rigs with a remaining useful life that Ensco assumes will extend beyond 2022, Ensco carried forward the 2022 operating assumptions for all remaining operating years.

(2)
EBITDA is calculated as net income excluding interest, taxes, depreciation and non-cash amortization of deferred revenue and expense.

(3)
Unlevered free cash flow is calculated as EBITDA less capital expenditures and unlevered taxes, adjusted for any changes in working capital.

(4)
Reflects estimates for the nine months ending December 31, 2017.

(5)
For any Atwood drilling rigs with a remaining useful life that Ensco assumes will extend beyond 2022, Ensco carried forward the 2022 operating assumptions for all remaining operating years.

(6)
Excludes capitalized interest and proceeds from asset sale.

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        The Ensco financial forecasts and the Atwood financial forecasts should be read together with the historical financial statements of Ensco and Atwood, respectively, which have been filed with the SEC, and the other information regarding Ensco and Atwood contained elsewhere in this joint proxy statement/prospectus. None of the Ensco financial forecasts or Atwood financial forecasts were prepared with a view toward public disclosure, nor were they prepared with a view toward compliance with the published guidelines of the SEC or the guidelines established by the American Institute of Certified Public Accountants for preparation and presentation of prospective financial information.

Certain Unaudited Financial Forecasts Prepared by the Management of Atwood

        The forward-looking financial information included in this section of this joint proxy statement/prospectus has been prepared by, and is the responsibility of, Atwood's management. PricewaterhouseCoopers LLP has neither examined, compiled nor performed any procedures with respect to such forward-looking financial information and, accordingly, PricewaterhouseCoopers LLP does not express an opinion or any other form of assurance with respect thereto. The PricewaterhouseCoopers LLP report incorporated by reference in this joint proxy statement/prospectus relates to Atwood's historical financial information. It does not extend to such forward-looking financial information and should not be read to do so.

        Atwood does not as a matter of course make public projections as to future earnings or other results of operations, other than providing estimates for certain financial items on a near-term basis on its regular earnings calls. For internal purposes and in connection with the process leading to the merger agreement, however, the management of Atwood prepared certain projections of future financial and operating performance of Atwood for the years 2017 through 2021 (sometimes referred to as the "Atwood Forecasts"). The management of Atwood also prepared certain projections of future financial and operating performance of Ensco for the years 2017 through 2021 (sometimes referred to as the "Atwood Forecasts for Ensco").

        The management of Atwood, after discussions with Ensco, also estimated the timing and amount of projected realization of annual savings from pre-tax cost synergies for the combined company (sometimes referred to as the "Atwood Synergies"). The Atwood Synergies are not reflected in the Atwood Forecasts or the Atwood Forecasts for Ensco. In addition, the management of Atwood prepared certain projections of future financial and operating performance of the combined company for the years 2017 through 2021 by combining the Atwood Forecasts, the Atwood Forecasts for Ensco and the Atwood Synergies, and making certain adjustments for the cost structure of the combined company as well as other adjustments compared to the standalone Atwood Forecasts for Ensco (such projections, as so adjusted, are sometimes referred to as the "Combined Company Forecasts"). We sometimes refer to all of the forecasts and synergies described above as the "forward-looking financial information."

        The forward-looking financial information is included in this joint proxy statement/prospectus solely because it was among the financial information made available, in whole or in part, to the Atwood Board, Ensco (only in the case of the Atwood Forecasts) and Atwood's financial advisor, Goldman Sachs, in connection with their respective evaluations of the merger. The forward-looking financial information was not prepared with a view toward public disclosure or with a view toward complying with GAAP, the published guidelines of the SEC regarding projections and forward-looking statements, or the guidelines established by the American Institute of Certified Public Accountants for preparation and presentation of prospective financial information. The development of the forward-looking financial information entailed numerous assumptions about Atwood and Ensco at a point in time, and the forward-looking information is subjective in many respects. Although the forward-looking financial information is presented with numerical specificity, the information reflects assumptions, estimates and judgments as to future events made by the management of Atwood. In the view of the management of Atwood, the forward-looking financial information was prepared on a reasonable basis

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and reflected the best then-currently available estimates and judgments at the time of its preparation, and presented at the time of its preparation, to the best of Atwood's management's knowledge and belief, reasonable projections of the future financial performance of Atwood, Ensco and the combined company. Neither Atwood's nor Ensco's independent registered public accounting firms, nor any other independent registered public accounting firm, has compiled, examined, or performed any procedures with respect to the forward-looking financial information, nor have they expressed any opinion or any other form of assurance on such information or its achievability, and assume no responsibility for, and disclaim any association with, the forward-looking financial information.

        Important factors that may affect actual results and cause the results to be different from the forward-looking financial information include: the ultimate timing, outcome and results of integrating the operations of Ensco and Atwood, general economic, regulatory and industrial conditions, changes in customer behavior, accuracy of certain accounting assumptions, changes in actual or projected cash flows, competitive pressures, changes in the demand for or price of oil and/or natural gas, changes in tax laws or accounting rules, changes in government regulations and regulatory requirements, particularly those related to offshore oil and natural gas exploration, structural changes in the oil and natural gas industry, costs and availability of resources and other matters described in the section "Risk Factors" in this joint proxy statement/prospectus. As the Atwood Forecasts, the Atwood Forecasts for Ensco and the Atwood Synergies are forward-looking statements, see also "Cautionary Statement Regarding Forward-Looking Statements" in this joint proxy statement/prospectus. In addition, the forward-looking financial information is not fact and does not take into account any circumstances or events occurring after the date that it was prepared and, accordingly, does not give effect to any changes to Ensco's operations or strategy that may be implemented after completion of the merger and, for the Atwood Forecasts and the Atwood Forecasts for Ensco, does not give effect to the merger. For the aforementioned reasons, the inclusion of the forward-looking information in this joint proxy statement/prospectus should not be regarded as an indication that the forward-looking information will be necessarily predictive of actual future events, and it should not be relied on as such. Actual results may be materially different from those contained in the forward-looking information.

        No one has made or makes any representation to any shareholder regarding the forward-looking financial information and Atwood has not made any representation to Ensco regarding the information included in the forward-looking financial information. The forward-looking financial information is not included in this joint proxy statement/prospectus in order to induce any shareholder to vote in favor of the merger or any of the other proposals to be voted on at the special meeting or to influence any shareholder to make any investment decision with respect to the merger. Except to the extent required by applicable federal securities laws, Ensco and Atwood do not intend, and expressly disclaim any responsibility, to update or otherwise revise the forward-looking financial information to reflect circumstances existing after the date when prepared or to reflect the occurrence of future events even in the event that any of the assumptions underlying the forward-looking financial information are shown to be in error.

        In light of the foregoing factors and the uncertainties inherent in the forward-looking financial information, Atwood shareholders are cautioned not to unduly rely on the forward-looking financial information included in this joint proxy statement/prospectus.

        Certain of the measures included in the forward-looking financial information may be considered non-GAAP financial measures, as noted below. Non-GAAP financial measures should not be considered in isolation from, or as a substitute for, financial information presented in compliance with GAAP, and non-GAAP financial measures as used by Atwood are not reported by all of Atwood's competitors in the offshore drilling industry and may not be comparable to similarly titled amounts used by other companies. Atwood encourages you to review the financial statements included in the sections entitled "Selected Historical Consolidated Financial Data of Ensco," "Selected Historical Consolidated Financial Data of Atwood" and "Unaudited Pro Forma Condensed Combined Financial

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Statements of Ensco" in this joint proxy statement/prospectus and Atwood's and Ensco's publicly-filed reports in their entirety and to not rely on any single financial measure.

        The following table presents a summary of the Atwood Forecasts. The Atwood Forecasts were reviewed with the Atwood Board. The Atwood Forecasts were also provided to Goldman Sachs for use in its financial analyses and opinion (summarized above in the section entitled "—Opinion of Financial Advisor to Atwood"), and Atwood also provided certain of the projections included in the Atwood Forecasts for calendar years 2017-2019 to Ensco.

 
Atwood Forecasts
(In millions)
 
Year Ending December 31,
 
2017E(1) 2018E 2019E 2020E 2021E

Revenue

$ 282 $ 345 $ 543 $ 717 $ 863

EBITDA(2)

$ 93 $ 7 $ 116 $ 265 $ 408

Unlevered Free Cash Flow(3)

$ 65 $ (153 ) $ (145 ) $ 163 $ 309

(1)
Represents estimates for the nine months ending December 31, 2017.

(2)
EBITDA is defined as earnings before interest, income taxes, depreciation and amortization. EBITDA is a non-GAAP financial measure, as it excludes amounts, or is subject to adjustments that effectively exclude amounts, included in the most directly comparable measure calculated and presented in accordance with GAAP in financial statements. EBITDA was used by management of Atwood to provide additional information in order to provide them with an alternative method for assessing Atwood's financial condition and operating results (including in comparison to other similar companies). These measures are not in accordance with, or a substitute for, GAAP, and may be different from or inconsistent with non-GAAP financial measures used by other companies. EBITDA should not be considered in isolation or as a substitute for net income, operating income, cash flows from operating activities or any other measure of financial performance presented in accordance with GAAP or as a measure of a company's profitability or liquidity.

(3)
Atwood Unlevered Free Cash Flow is defined as EBITDA less taxes less capital expenditures plus proceeds from disposal of assets (if any) plus changes in net working capital. Atwood Unlevered Free Cash Flow was used by Atwood's management to provide additional information with respect to available cash and liquidity. These measures are not in accordance with, or a substitute for, GAAP, and may be different from or inconsistent with non-GAAP financial measures used by other companies. Atwood Unlevered Free Cash Flow should not be considered in isolation or as a substitute for cash flows from operating activities or any other measure of financial performance presented in accordance with GAAP or as a measure of a company's profitability or liquidity.

        The following table presents a summary of the Atwood Forecasts for Ensco. The Atwood Forecasts for Ensco were reviewed with the Atwood Board. The Atwood Forecasts for Ensco were also provided to Goldman Sachs for use in its financial analyses and opinion (summarized above in the section entitled "—Opinion of Financial Advisor to Atwood").

 
Atwood Forecasts for Ensco
(In millions)
 
Year Ending December 31,
 
2017E(1) 2018E 2019E 2020E 2021E

Revenue

$ 1,360 $ 1,841 $ 1,831 $ 1,982 $ 2,155

EBITDA(2)

$ 413 $ 548 $ 579 $ 763 $ 953

Unlevered Free Cash Flow(3)

$ 141 $ 171 $ 360 $ 685 $ 831

(1)
Represents estimates for the nine months ending December 31, 2017.

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(2)
EBITDA is defined as earnings before interest, income taxes, depreciation and amortization. EBITDA is a non-GAAP financial measure, as it excludes amounts, or is subject to adjustments that effectively exclude amounts, included in the most directly comparable measure calculated and presented in accordance with GAAP in financial statements. EBITDA was used by management to provide additional information in order to provide them with an alternative method for assessing financial condition and operating results (including in comparison to other similar companies). These measures are not in accordance with, or a substitute for, GAAP, and may be different from or inconsistent with non-GAAP financial measures used by other companies. EBITDA should not be considered in isolation or as a substitute for net income, operating income, cash flows from operating activities or any other measure of financial performance presented in accordance with GAAP or as a measure of a company's profitability or liquidity.

(3)
Atwood forecasted Ensco Unlevered Free Cash Flow is defined as EBITDA less taxes less capital expenditures less mobilization costs plus proceeds from disposal of assets (if any) plus changes in net working capital. Mobilization costs are defined as the cash costs associated with rig mobilization. Atwood forecasted Ensco Unlevered Free Cash Flow was used by Atwood's management to provide additional information with respect to available cash and liquidity. These measures are not in accordance with, or a substitute for, GAAP, and may be different from or inconsistent with non-GAAP financial measures used by other companies. Atwood forecasted Ensco Unlevered Free Cash Flow should not be considered in isolation or as a substitute for cash flows from operating activities or any other measure of financial performance presented in accordance with GAAP or as a measure of a company's profitability or liquidity.

        The following table presents a summary of the Combined Company Forecasts. The Combined Forecasts were reviewed with the Atwood board of directors. The Combined Company Forecasts were also provided to Goldman Sachs for use in its financial analyses and opinion (summarized above in the section entitled "—Opinion of Financial Advisor to Atwood").

 
  Combined Company Forecasts
(In millions)
 
 
  Year Ending December 31,
 
 
  2017E(1)   2018E   2019E   2020E   2021E  

Revenue

  $ 1,642   $ 2,187   $ 2,374   $ 2,699   $ 3,018  

EBITDA(2)

  $ 451   $ 549   $ 721   $ 1,040   $ 1,361  

Unlevered Free Cash Flow(3)

  $ 150   $ 12   $ 241   $ 861   $ 1,140  

(1)
Represents estimates for the nine months ending December 31, 2017.

(2)
EBITDA is defined as earnings before interest, income taxes, depreciation and amortization. EBITDA is a non-GAAP financial measure, as it excludes amounts, or is subject to adjustments that effectively exclude amounts, included in the most directly comparable measure calculated and presented in accordance with GAAP in financial statements. EBITDA was used by Atwood's management to provide additional information in order to provide them with an alternative method for assessing Atwood's, Ensco's and the combined company's financial condition and operating results (including in comparison to other similar companies). These measures are not in accordance with, or a substitute for, GAAP, and may be different from or inconsistent with non-GAAP financial measures used by other companies. EBITDA should not be considered in isolation or as a substitute for net income, operating income, cash flows from operating activities or any other measure of financial performance presented in accordance with GAAP or as a measure of a company's profitability or liquidity.

(3)
Atwood forecasted Combined Company Unlevered Free Cash Flow is defined as EBITDA less taxes less capital expenditures less mobilization costs plus proceeds from disposal of assets (if any)

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        The following table presents a summary of the Atwood Synergies, which were reviewed with the Atwood Board and provided to Goldman Sachs for use in its financial analyses and opinion (summarized above in the section entitled "—Opinion of Financial Advisor to Atwood").

 
  Atwood Synergies
(In millions)
 
 
  Year Ending December 31,
 
 
  2017E   2018E   2019E   2020E   2021E  

Pre-Tax Cost Synergies

  $ 4   $ 49   $ 65   $ 65   $ 65  

Board of Directors and Executive Officers of Ensco Following the Merger

        The current directors of Ensco are: Paul E. Rowsey, III, Carl Trowell, J. Roderick Clark, Roxanne J. Decyk, Mary E. Francis CBE, C. Christopher Gaut, Gerald W. Haddock, Francis S. Kalman and Keith O. Rattie. At the Effective Time, Ensco will cause two directors currently serving on the Atwood Board, Jack E. Golden and Phil D. Wedemeyer, to be appointed to the Ensco Board and will expand the Ensco Board to the extent necessary in connection with appointing such additional directors. The two additional directors were proposed by Atwood following the execution of the merger agreement and have been mutually agreed upon by Ensco and Atwood. All Ensco directors are elected annually to serve until the next annual meeting and until their successors are elected.

        Ensco's executive officers will remain the same following the merger, and none of Atwood's executive officers are expected to have any executive officer positions with the combined company.

Public Trading Markets

        The Ensco Class A ordinary shares are quoted on the NYSE under the symbol "ESV," and the Atwood common stock is quoted on the NYSE under the symbol "ATW." Upon completion of the merger, the Atwood common stock will be delisted from the NYSE and deregistered under the Exchange Act. The Ensco Class A ordinary shares issuable in the merger will be listed on the NYSE and will be freely transferable under the Securities Act.

No Appraisal or Dissenters' Rights

        Atwood shareholders who dissent to the merger will not have rights to an appraisal of the fair value of their shares. Under the TBOC, shareholders generally have appraisal rights in the event of a merger or consolidation. However, these appraisal rights are not available if (i) the shares held by the shareholder are part of a class of shares listed on a national securities exchange or held of record by at least 2,000 holders (ii) the shareholder is not required to accept for his or her shares any consideration that is different than the consideration to be provided to any other holder of shares of the same class held by the shareholder, and (iii) the shareholder is not required to accept any consideration other than shares of a corporation that satisfy the requirements in clause (i) above. Because Ensco Class A ordinary shares are listed on the NYSE, a national securities exchange, and are expected to continue to be so listed following the merger, and because the merger otherwise satisfies the foregoing

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requirements, Atwood shareholders will not be entitled to appraisal or dissenters' rights in the merger with respect to their shares of Atwood common stock.

Accounting Treatment of the Merger

        Ensco prepares its financial statements in accordance with GAAP. The merger will be accounted for using the acquisition method of accounting with Ensco being considered the acquirer of Atwood for accounting purposes. This means that Ensco will allocate the purchase price to the fair value of Atwood's tangible and intangible assets and liabilities at the acquisition date, with the excess purchase price, if any, being recorded as goodwill, or the excess of the fair value of Atwood's tangible and intangible assets and liabilities at the acquisition date over the purchase price, if any, being recognized in Ensco's earnings. Under the acquisition method of accounting, goodwill is not amortized but is tested for impairment at least annually.

Regulatory Approvals Required for the Merger

        To complete the merger, Ensco and Atwood must make filings with and obtain authorizations, approvals or consents from a number of regulatory authorities. These approvals include clearance under the HSR Act as well as approval (subject to official notice of issuance) from the NYSE to list the new Ensco Class A ordinary shares to be issued as merger consideration to Atwood shareholders.

        Antitrust Considerations.    The HSR Act, and the rules and regulations thereunder, provide that the transaction may not be completed until pre-merger notification filings have been made with the DOJ and the FTC and the applicable waiting period has expired or is terminated. Even after the waiting period expires or is terminated, the DOJ and the FTC retain the authority to challenge the transaction on antitrust grounds before or after the transaction is completed. On June 9, 2017, Ensco and Atwood filed a Premerger Notification and Report Form pursuant to the HSR Act with the DOJ and the FTC. On June 27, 2017, the DOJ and the FTC granted early termination of the waiting period under the HSR Act.

        Timing.    Ensco and Atwood cannot assure you that all of the regulatory approvals described above will be obtained, and, if obtained, Ensco and Atwood cannot assure you as to the date of any approvals or the absence of any litigation challenging such approvals. Likewise, Ensco and Atwood cannot assure you that the DOJ, the FTC or any state attorney general will not attempt to challenge the merger on antitrust grounds, and, if such a challenge is made, we cannot assure you as to its result.

        Ensco and Atwood are not aware of any material governmental approvals or actions that are required for completion of the merger other than those described above. It is presently contemplated that if any such additional governmental approvals or actions are required, those approvals or actions will be sought. There can be no assurance, however, that any additional approvals or actions will be obtained.

Litigation Relating to the Merger

        On June 23, 2017, a putative class action captioned Bernard Stern v. Atwood Oceanics, Inc., et al, was filed in the U.S. District Court for the Southern District of Texas against Atwood, Atwood's directors, Ensco and Merger Sub. The Stern complaint generally alleges that the directors and Atwood disseminated a false or misleading registration statement, referring to this registration statement as filed with the SEC on June 16, 2017, which omitted material information regarding the proposed merger in violation of Section 14(a) of the Exchange Act. Specifically, the complaint alleges that Atwood and the directors omitted material information regarding the parties' financial projections, the analysis performed by Goldman Sachs in support of its fairness opinion, the timing and nature of communications regarding post-transaction employment of Atwood's directors and officers, potential conflicts of interest of Goldman Sachs, and whether there were further discussions with another

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potential acquirer of Atwood following the May 30, 2017 announcement of the merger. The complaint further alleges that the Atwood directors, Ensco, and Merger Sub are liable for these violations as "control persons" of Atwood under Section 20(a) of the Exchange Act. With respect to Ensco, the complaint alleges that Ensco had direct supervisory control over the composition of the registration statement. The complaint seeks injunctive relief, including to enjoin the merger, rescission or rescissory damages in the event the merger is consummated, and an award of attorneys' fees, in addition to other relief. On June 27, June 29 and June 30, 2017, additional putative class actions captioned Joseph Composto v. Atwood Oceanics, Inc., et al, Booth Family Trust v. Atwood Oceanics, Inc., et al, and Mary Carter v. Atwood Oceanics, Inc., et al, respectively, were filed in the U.S. District Court for the Southern District of Texas against Atwood and Atwood's directors. These actions allege violations of Sections 14(a) and 20(a) of the Exchange Act by Atwood and Atwood's directors similar to those alleged in the Stern complaint; however, neither Ensco nor Merger Sub is named as a defendant in these actions.

        Additional lawsuits arising out of the merger may be filed in the future. There can be no assurance that any of the defendants will be successful in the outcome of the pending or any potential future lawsuits. A preliminary injunction could delay or jeopardize the completion of the merger, and an adverse judgment granting permanent injunctive relief could indefinitely enjoin the completion of the merger. Ensco and Atwood believe that the lawsuits are without merit and intend to defend vigorously against the lawsuits and any other future lawsuits challenging the transaction.

Atwood's Directors and Officers Have Financial Interests in the Merger

        In considering the recommendation of the Atwood Board that Atwood's shareholders vote "FOR" the Atwood Merger Proposal, Atwood shareholders should be aware that Atwood's directors and executive officers have financial interests in the merger that may be different from, or in addition to, those of Atwood shareholders generally. The Atwood Board was aware of these interests and considered them, among other matters, in approving the merger agreement and making its recommendation that Atwood shareholders approve the Atwood Merger Proposal. For purposes of all of Atwood's agreements and plans described below, the completion of the merger will constitute a change of control.

Equity Compensation Awards

        Pursuant to the merger agreement, equity compensation awards held by Atwood's directors and executive officers as of the Effective Time will be treated as follows:

        Options.    The merger agreement provides that stock option awards outstanding immediately prior to the Effective Time will be exchanged for Converted Options. All of Atwood's outstanding stock options previously vested. The Converted Options will otherwise remain subject to the same terms and conditions as the corresponding Existing Options. The number of Ensco Class A ordinary shares subject to the Converted Options will be determined by multiplying the number of shares of Atwood common stock subject to the Existing Options immediately prior to the Effective Time by the exchange ratio, rounded down to the nearest whole share, and the exercise price per share of the Converted Options will equal the per share exercise price of the Existing Options immediately prior to the Effective Time divided by the exchange ratio, rounded up to the nearest whole cent.

        Restricted Stock Units.    Pursuant to the applicable Atwood incentive plans, all Atwood RSUs held by Atwood's directors and employees shall vest upon the Effective Time. Time-Based RSUs that so vest will be settled through the issuance of Ensco Class A ordinary shares equal to the number of vested Time-Based RSUs multiplied by the exchange ratio. Performance-Based RSUs will vest at the Effective Time at the higher of target level of performance or the amount determined by the compensation committee of the Atwood Board in its sole discretion (but capped at 200% of target level) and the

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number of Performance-Based RSUs that vest will be settled through the issuance of Ensco Class A ordinary shares equal to the number of vested Performance-Based RSUs multiplied by the exchange ratio. Accrued cash dividend equivalents on Atwood RSUs will also vest and be cashed out at the same time. Atwood Cash Units will be treated as specified in the applicable award agreement. The Atwood Cash Units are performance vesting awards that will vest in full upon the Effective Time at the higher of target level of performance or the amount determined by the compensation committee of the Atwood Board (up to 200% of target level) and will be paid in cash based on the closing price of Atwood common stock on the last trading day prior to the closing date. Accrued cash dividend equivalents on the Atwood Cash Units will also vest and be cashed out at the same time. As of August 17, 2017, the Atwood Board had made no determination regarding the level at which the Performance-Based RSUs or Atwood Cash Units will vest upon the Effective Time.

        The following table sets forth the number of Time-Based RSUs and Performance-Based RSUs (at target level of performance) held by Atwood's executive officers and non-employee directors as of August 17, 2017, along with accrued dividend equivalents (at target level of performance for Performance-Based RSUs) as of August 17, 2017:

Name
  Time-Based
RSUs(1)
  Performance-Based
RSUs (at target)(1)
  Cash Units
(at target)(1)
  Accrued Dividend
Equivalents(2)
 

Executive Officers:

                         

Robert J. Saltiel

    494,638     242,061     120,184   $ 127,941  

Mark W. Smith

    123,764     70,351       $ 22,411  

Arthur M. Polhamus

    121,883     75,102       $ 27,003  

Barry M. Smith

    118,636     73,180       $ 26,321  

Walter A. Baker

    115,059     70,309       $ 25,287  

Stuart Allen

    76,702     45,174       $ 18,236  

John Gidley

    56,971     31,601       $ 12,963  

Mark Monroe

    81,269     43,483       $ 8,428  

Evelyn Nordin

    52,338     25,692       $ 6,136  

Non-Employee Directors:

   
 
   
 
   
 
   
 
 

George Dotson

    19,157           $ 0  

Jack Golden

    31,737           $ 3,445  

Hans Helmerich

    22,497           $ 3,591  

Jeffrey A. Miller

    28,532           $ 0  

James Montague

    50,347           $ 22,377  

Phil D. Wedemeyer

    36,035           $ 6,991  

(1)
The Atwood RSUs and Atwood Cash Units granted to Atwood's executive officers originally were scheduled to vest three years after the applicable grant date (or, with respect to Time-Based RSUs grants in November 2016, in three equal annual installments following the grant date), provided that the Atwood RSUs granted in connection with the non-competition and non-solicitation agreements, as described below were subject to a two year vesting provision. Atwood RSUs granted to Atwood's non-employee directors were originally scheduled to vest 13 months after the applicable grant date, but provide for settlement on a deferred basis pursuant to Atwood's deferred compensation plan for non-employee directors. The amount shown for Atwood's non-employee directors includes amounts that have previously vested.

(2)
Assumes target level vesting for Performance-Based RSUs and Atwood Cash Units. Actual dividend equivalent payments will depend on the actual vesting level for the Performance-Based RSUs and Atwood Cash Units and therefore may be higher than the amounts shown.

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Executive Change of Control Agreements

        Each of Atwood's executive officers is party to a change of control agreement that addresses the terms of the executive's compensation in the event of a termination of employment due to a change of control. Each agreement contains "double-trigger" requirements for payments relating to termination of employment other than for cause within two years following a change of control.

        Under the change of control agreements, if Atwood terminates the executive's employment without "cause" or the executive terminates the executive's employment for "good reason" (each as defined in the agreement) within 24 months after a change of control of Atwood, Atwood will be required to pay to the executive in a lump sum (x) the executive's accrued salary, pro rata target bonus for the year of termination and accrued vacation (the "Accrued Amounts") and (y) an amount equal to 2.0 times for each vice president or 2.5 times for each named executive officer and senior vice president (3.0 times in the case of Mr. Saltiel) to determine the sum of (a) the executive's annual salary plus (b) the executive's target annual bonus.

        In addition, following such termination, the executive and the executive's spouse and/or family, as applicable, will be entitled to continued participation in Atwood's welfare benefit plans, policies and programs for a period of 24 months (the "Atwood Welfare Continuation Benefit") and any outstanding stock options held by the executive will remain exercisable for one year after termination; provided that in no event will any stock options remain exercisable later than the earlier of (i) the original expiration date of such stock options or (ii) the tenth anniversary of the original grant date for such stock options. If the executive's employment is terminated due to disability within 24 months after a change of control of Atwood, Atwood will be required to pay to the executive the Accrued Amounts and provide the Atwood Welfare Continuation Benefit. If the executive's employment is terminated due to death within 24 months after a change of control of Atwood, Atwood will be required to pay to the executive's estate the Accrued Amounts and provide to executive's spouse and/or family, as applicable, the Atwood Welfare Continuation Benefit. With respect to excise taxes on any parachute payment under the change of control agreement, the agreement provides that the executive will be liable for such excise taxes; provided, however, that if reduction of the payments under the agreement to avoid excise taxes would result in a larger net after-tax payment to the executive, the payments under the agreement will be reduced.

Non-Competition and Non-Solicitation Agreements

        Each of Atwood's executive officers is subject to a non-competition and non-solicitation agreement pursuant to which specified time-vesting cash awards and Atwood RSUs were granted in 2016, which awards were originally scheduled to vest in May 2018. The cash award will fully vest and become payable upon the Effective Time, and the Atwood RSUs will fully vest and be treated as specified above.

Benefit Equalization Plan

        Each of Atwood's executive officers participates in Atwood's Benefit Equalization Plan, which permits the executive to make tax deferred contributions, including with respect to amounts that exceed certain Internal Revenue Code limits. The Benefit Equalization Plan was frozen as of January 1, 2017 and all amounts under the plan are fully vested. Amounts deferred under the Benefit Equalization Plan will generally be paid following the Effective Time or the executive officers separation from service in accordance with the executive officer's original deferral elections under the plan.

Salary Continuation Plan

        Executive officers are covered under Atwood's Salary Continuation Plan, formerly named the Executive Life Insurance Plan, which provides for salary continuation to the executive's beneficiary

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upon the executive's death while employed by Atwood. Payments equal to 2.5 times annual salary are payable in 30 installments or, in the event of death due to accidental causes, payments equal to five times annual salary are payable in 60 installments. If the executive officer terminates employment within 30 months following a change of control, the death benefit is payable if the executive dies during that 30-month period.

Quantification of Payments and Benefits to Atwood's Named Executive Officers

        The following table sets forth the information required by Item 402(t) of Regulation S-K regarding the compensation that is based on or otherwise relates to the merger and that may be paid or become payable to Atwood's named executive officers, which is referred to as the "golden parachute" compensation. The information set forth in the table below is intended to comply with Item 402(t) of Regulation S-K, which requires disclosure of information about certain compensation for each of Atwood's named executive officers that is based on or otherwise relates to the merger.

        The amounts indicated below are estimates based on the material assumptions described in the notes to the table below, which may or may not actually occur. Some of these assumptions are based on information not currently available and, as a result, the actual amounts, if any, that may be paid or become payable to a named executive officer may differ materially from the amounts set forth below. Furthermore, for purposes of calculating such amounts, Atwood has assumed the following:

 
  Cash ($)    
   
   
   
 
 
   
  Equity ($)    
 
 
   
   
  NC/NS
Cash(3)
  Accrued
Dividend
Equivalents(4)
  Atwood
Cash
Units(5)
  Perquisites/
Benefits(6)
   
 
Name(1)
  Salary(1)   Bonus(2)   (7)   (8)   Total ($)  

Robert J. Saltiel

    2,442,000     3,157,874     1,322,750     127,941     1,212,657     41,459     3,292,311     1,611,158     13,208,150  

Mark W. Smith

    925,000     875,278     481,000     22,411         26,479     823,773     468,256     3,622,197  

Arthur M. Polhamus

    960,000     908,397     499,200     27,003         13,190     811,253     499,879     3,718,922  

Barry M. Smith

    932,500     882,375     484,900