Aspen Insurance Holdings Limited Announces Agreement To Sell Ordinary Shares By Shareholders

Hamilton, Bermuda: June 28, 2007 €” Aspen Insurance Holdings Limited ("Aspen") (NYSE: AHL; BSX: AHL.BH) announced today that two of its shareholders, The Blackstone Group and DLJ Merchant Banking Partners have agreed to sell 5,707,625 ordinary shares of Aspen and 2,219,668 ordinary shares of Aspen, respectively, in an underwritten public offering. Following the completion of the offering, The Blackstone Group and DLJ Merchant Banking Partners, a private equity investment affiliate of Credit Suisse, will no longer own any shares of Aspen.

Credit Suisse is acting as the sole book-running manager for the offering. Credit Suisse proposes to offer Aspen's ordinary shares from time to time for sale in one or more transactions on the NYSE, in the over-the-counter market, through negotiated transactions or otherwise at market prices prevailing at the time of sale, at prices related to prevailing market prices or at negotiated prices. Aspen will not receive any proceeds from the sale of ordinary shares by The Blackstone Group and DLJ Merchant Banking Partners.

Commenting on the offering, Chris O'Kane, Aspen's Chief Executive Officer said: "After five years, Blackstone and DLJMB, two of our founding shareholders, are selling their shares as part of their liquidity strategy.  We want to thank them for their support in our establishment and growth since 2002."

The ordinary shares are being sold pursuant to Aspen's effective shelf registration statement previously filed with the Securities and Exchange Commission. A prospectus supplement relating to the ordinary shares offering will be filed with the Securities Exchange Commission. When available, a written prospectus for the offering meeting the requirements of Section 10 of the Securities Act of 1933, as amended, may be obtained from Credit Suisse by contacting Credit Suisse Securities (USA) LLC, Prospectus Department, at One Madison Avenue, New York, NY 10010, telephone (800) 221-1037.

This press release shall not constitute an offer to sell or the solicitation of an offer to buy nor shall there be any sale of these securities in any jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such jurisdiction. Any offering of ordinary shares will be made only by means of a written prospectus meeting the requirements of Section 10 of the Securities Act of 1933, as amended.

About Aspen Insurance Holdings Limited

Aspen Insurance Holdings Limited was established in June 2002. Aspen is a Bermudian holding company that provides property and casualty reinsurance in the global market, property and liability insurance principally in the United Kingdom and the United States and specialty insurance and reinsurance consisting mainly of marine and energy and aviation worldwide. Aspen's operations are conducted through its wholly-owned subsidiaries located in London, Bermuda and the United States: Aspen Insurance UK Limited, Aspen Insurance Limited and Aspen Specialty Insurance Company. Aspen has four operating segments: property reinsurance, casualty reinsurance, specialty insurance and reinsurance and property and casualty insurance. For more information about Aspen, please visit Aspen's website at http://www.aspen.bm.

Application of the Safe Harbor of the Private Securities Litigation Reform Act of 1995:

This press release contains, and Aspen's earnings conference call may contain, written or oral "forward-looking statements" within the meaning of the U.S. federal securities laws. These statements are made pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. Forward-looking statements include all statements that do not relate solely to historical or current facts, and can be identified by the use of words such as "expect," "intend," "plan," "believe," "project," "anticipate," "seek," "will," "estimate," "may," "continue," and similar expressions of a future or forward-looking nature.

All forward-looking statements address matters that involve risks and uncertainties. Accordingly, there are or will be important factors that could cause actual results to differ materially from those indicated in these statements. Aspen believes these factors include, but are not limited to: the impact that our future operating results, capital position and rating agency and other considerations have on the execution of any capital management initiatives; the impact of any capital management initiatives on our financial condition; the impact of acts of terrorism and related legislation and acts of war; the possibility of greater frequency or severity of claims and loss activity, including as a result of natural or man-made catastrophic events, than our underwriting, reserving, reinsurance purchasing or investment practices have anticipated; evolving interpretive issues with respect to coverage as a result of Hurricanes Katrina, Rita and Wilma; the level of inflation in repair costs due to limited availability of labor and materials after catastrophes; the effectiveness of Aspen's loss limitation methods; changes in the availability, cost or quality of reinsurance or retrocessional coverage; the reliability of, and changes in assumptions to, catastrophe pricing, accumulation and estimated loss models; loss of key personnel; a decline in our operating subsidiaries' ratings with Standard & Poor's, a division of the McGraw-Hill Companies, Inc., A.M. Best Company or Moody's Investors Service; changes in general economic conditions including inflation, foreign currency exchange rates, interest rates and other factors that could affect our investment portfolio; increased competition on the basis of pricing, capacity, coverage terms or other factors; decreased demand for Aspen's insurance or reinsurance products and cyclical downturn of the industry; changes in governmental regulations or tax laws in jurisdictions where Aspen conducts business; Aspen or its Bermudian subsidiary becoming subject to income taxes in the United States or the United Kingdom; the effect on insurance markets, business practices and relationships of ongoing litigation, investigations and regulatory activity by the New York State Attorney General's office and other authorities concerning contingent commission arrangements with brokers and bid solicitation activities; the total industry losses resulting from Hurricanes Katrina, Rita and Wilma and any other events, and the actual number of Aspen's insureds incurring losses from these storms; and with respect to Hurricanes Katrina, Rita and Wilma, Aspen's continued reliance on loss reports received from cedants and loss adjustors, Aspen's reliance on industry loss estimates and those generated by modeling techniques, the impact of these storms on Aspen's reinsurers, changes in the assumptions on flood damage exclusions as a result of prevailing lawsuits and case law, any changes in Aspen's reinsurers' credit quality, the amount and timing of reinsurance recoverables and reimbursements actually received by Aspen from its reinsurers and the overall level of competition and the related demand and supply dynamics as contracts come up for renewal. For a more detailed description of these uncertainties and other factors, please see the "Risk Factors" section in Aspen's Annual Reports on Form 10-K for the year ended December 31, 2006 as filed with the U.S. Securities and Exchange Commission on February 22, 2007. Aspen undertakes no obligation to publicly update or revise any forward-looking statements, whether as a result of new information, future events or otherwise. Readers are cautioned not to place undue reliance on these forward- looking statements, which speak only as of the dates on which they are made.

Investor and Press Contacts:

Aspen Insurance Holdings Limited                      

Tania Kerno, Head of Communications                    +44 (0) 20 7184 8855

Noah Fields, Head of Investor Relations                  +1 (441) 297-9382

European Press Contact:

                              Citigate Dewe Rogerson                                           +44 (0) 20 7638 9571

                              Sarah Gestetner/Justin Griffiths/Hannah Seward           

North American Press Contact:                 

                              Abernathy MacGregor                                               +1 (212) 371-5999

                              Eliza Johnson