Ensco plc (NYSE: ESV) announced today that the Company has agreed to terminate its American Depositary Share (ADS) facility and convert its outstanding ADSs into Class A Ordinary Shares. Recent regulatory developments involving shares of companies domiciled in the U.K. have facilitated the change, and Ensco expects its Class A Ordinary Shares to begin trading on the NYSE on 22 May 2012 under the same symbol “ESV.”

Each Ensco ADS currently represents one Class A Ordinary Share of the Company. The conversion will allow Ensco shareholders to directly own and trade Class A Ordinary Shares on the NYSE, which is a requirement to be eligible for the S&P 500 Index.

Ensco previously was included in the S&P 500 Index until December 2009 when it changed its corporate domicile to the U.K. from Delaware. Regulations for U.K. companies at the time required Ensco’s Class A Ordinary Shares to be traded in ADS form and, since eligibility rules for the S&P 500 Index exclude companies listed in ADS form, Ensco was removed from the index. The Company’s decision to convert to a Class A Ordinary Share listing will restore Ensco’s eligibility for the S&P 500 Index, although there is no assurance that Ensco will be added to the index in the future.

The majority of Ensco shareholders will be unaffected by the conversion from ADSs to Class A Ordinary Shares. Shareholders who hold their ADSs in a bank or brokerage account will not be required to take any action. Shareholders possessing physical certificates or who hold their ADSs in an account with the Company’s transfer agent (holders of record) will receive instructions on how to convert their ADSs.

The conversion to Class A Ordinary Shares will not influence the voting process for the upcoming Annual General Meeting of Shareholders to be held on 22 May 2012. Votes already cast will be voted as directed. Shareholders who have not yet voted may cast their votes per the voting instructions included in the proxy materials through 16 May 2012. All Ensco shareholders are encouraged to vote their shares by tomorrow’s deadline.

Ensco plc (NYSE: ESV) brings energy to the world as a global provider of offshore drilling services to the petroleum industry. For 25 years, the company has focused on operating safely and exceeding customer expectations. In the most recent independent survey of customers completed by EnergyPoint Research, Ensco received the top score in 13 of 17 categories including the #1 rating for total customer satisfaction. Operating the world’s newest ultra-deepwater fleet and largest fleet of active premium jackups, Ensco has a major presence in the most strategic offshore basins across six continents. To learn more about Ensco, visit www.enscoplc.com. Ensco plc is an English limited company (England No. 7023598) with its registered office and corporate headquarters located at 6 Chesterfield Gardens, London W1J 5BQ.

Statements contained in this press release that are not historical facts are forward-looking statements within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. Forward-looking statements include words or phrases such as “anticipate,” “believe,” “estimate,” “expect,” “intend,” “plan,” “project,” “could,” “may,” “might,” “should,” “will” and similar words and specifically include statements regarding Ensco’s plan to terminate its ADS facility, list its Class A Ordinary Shares on the NYSE and restore its eligibility for the S&P 500 Index. Such statements are subject to numerous risks, uncertainties and assumptions that may cause actual results to vary materially from those indicated, including the eligibility and continued approval of Ensco’s Class A Ordinary Shares for deposit, book entry and clearing services of The Depository Trust Company and its related parties; the approval, subject to official notice of issuance, of the NYSE listing application for Class A Ordinary Shares; the sole discretion and determination by Standard & Poor’s that Ensco meets all other criteria for eligibility for the S&P 500 Index; and the Company’s ultimate acceptance into the S&P 500 Index in the future. In addition to the numerous factors described above, you should also carefully read and consider “Item 1A. Risk Factors” in Part I and “Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations” in Part II of our most recent annual report on Form 10-K, as updated in our subsequent quarterly reports on Form 10-Q, which are available on the SEC’s website at www.sec.gov or on the Investor Relations section of our website at www.enscoplc.com.Each forward-looking statement speaks only as of the date of the particular statement, and we undertake no obligation to publicly update or revise any forward-looking statements, except as required by law.