AHL Aspen Insurance Holdings Limited Ordinary Shares

A.M. Best Co. has affirmed the financial strength ratings of A (Excellent) and the issuer credit ratings (ICR) of �a� of Aspen Insurance UK Limited (AIUK) (United Kingdom) and Aspen Insurance Limited (AIL) (Bermuda). A.M. Best has also affirmed the ICR of �bbb� of Aspen Insurance Holdings Limited (Aspen) (Bermuda) [NYSE: AHL], the non-operating holding company of the Aspen group of companies, and the debt rating of �bbb� on the USD 250 million 6% senior unsecured notes issued by Aspen. The USD 200 million perpetual non-cumulative preference shares and the USD 230 million perpetual preferred income equity replacement securities, also issued by Aspen, have been upgraded to �bb+� from �bb�. In addition, A.M. Best has affirmed the ratings for Aspen�s universal shelf registrations of �bbb,� �bbb-� and �bbb-� on senior unsecured debt, subordinated debt and the junior subordinated debt and upgraded the preferred stock to �bb+� from �bb�. The outlook for all ratings remains stable. A.M. Best believes that AIL and AIUK are likely to maintain excellent risk-adjusted capitalisation in 2008. Additionally, AIL and AIUK will continue to benefit from the financial flexibility of their parent, which is expected to maintain excellent consolidated risk-adjusted capitalisation in 2008. Aspen continues to balance its spread of risk between AIL and AIUK through the use of the group�s intra-group quota share arrangements. In A.M. Best�s opinion, the level of capital held at AIL is likely to be sufficiently strong to support the company�s increased underwriting exposure, arising from the overall higher reinsurance ceded through quota shares from AIUK and its new reinsurance arrangement with Aspen Underwriting Limited (AUL) (Aspen�s corporate member for Lloyd�s Syndicate 4711). A.M. Best believes that AIL and AIUK will report strong pre-tax profits in 2008. Good underwriting performance is anticipated, notwithstanding the impact of hurricanes Gustav and Ike and softening in rates. A.M. Best believes that Aspen will generate a positive, albeit lower investment return in 2008, despite the turbulence in the financial markets. Financial performance for both entities is expected to be enhanced by the group�s conservative investment strategy. Further ahead, A.M. Best expects prudent reserving practices and the group�s comprehensive reinsurance programme to support stable results. In A.M. Best�s opinion, AIL and AIUK benefit from Aspen�s profile, which has developed as a result of the range of business written and its wide spread of branch operations. Both entities underwrite a well-diversified portfolio of property, casualty and specialty business (insurance and reinsurance), supported by the intra-group quota share arrangements. Additionally, AIL underwrites a book of structured property and casualty risks. AIUK is the largest subsidiary within AHL, representing approximately 75% of the group�s consolidated premium income in 2008, whilst AIL�s income before intra-group quota shares is expected to contribute approximately 20%. A.M. Best anticipates that the proportion of premium written by AIUK will decline in the future, as Aspen expands through syndicate 4711 and Aspen Specialty Insurance Company (ASIC) (wholly owned U.S. subsidiary of Aspen). The premium contribution from AIL is expected to remain relatively unchanged. Founded in 1899, A.M. Best Company is a global full-service credit rating organization dedicated to serving the financial and health care service industries, including insurance companies, banks, hospitals and health care system providers. For more information, visit www.ambest.com.