Ambac Assurance UK Limited ('AUK') Instructs the Association of British Insurers to Conduct an Initial Holdings Enquiry for the Metronet Rail SSL & BCV Bonds.

NEW YORK -- AUK has instructed the Association of British Insurers (the "ABI") to undertake an initial holdings enquiry of the AUK guaranteed Metronet SSL and BCV bonds. The holdings enquiry has been instructed purely for informational purposes at this juncture and does not relate to any specific proposal in relation to the Metronet bonds at this time.

Any holders of the Metronet SSL and BCV bonds who are not members of the ABI and wish to record their presence with AUK may do so by contacting Paul Burke on the above details or the Bond Trustee for the attention of Stuart Harding ([e-mail]). Deutsche is the Bond Trustee under the Bond Trust Deed governing the SSL and BCV bonds.

AUK insures the PS165m 2.8756 per cent. Index-Linked Guaranteed Secured Bonds due 2032 issued by Metronet SSL Finance plc [ISIN XS0166412279] and the PS350m 5.305 per cent. Fixed Rate Guaranteed Secured Bonds due 2032 issued by Metronet BCV Finance plc [ISIN XS0166411115]. The debt was issued under Public Private Partnership contracts to finance the operation, maintenance and the initial phase of asset upgrades for part of the London Underground.

Further information has been released pursuant to a press release by AUK dated 13th February 2008.

AUK's unconditional and irrevocable guaranty remains in full force and effect.

Forward-Looking Statements

This release contains statements about our future results that may constitute "forward-looking statements" within the meaning of the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. These statements are based on management's current expectations and are subject to uncertainty and changes in circumstances. Actual results may differ materially from those included in these statements due to a variety of factors. More information about these factors is contained in Ambac Financial Group Inc.'s (ultimate parent company to AUK) ("Ambac") filings with the Securities and Exchange Commission. There are a variety of factors, many of which are beyond Ambac's control, which affect the operations, performance, business strategy and results and could cause its actual results to differ materially from the expectations and objectives expressed in any forward-looking statements. Readers are cautioned not to place undue reliance on forward-looking statements which speak only as of the date they are made. Ambac does not undertake to update forward-looking statements to reflect the impact of circumstances or events that arise after the date the forward-looking statements are made. The reader should, however, consult any further disclosures Ambac may make in its future filings of its reports on Form 10-K, Form 10-Q and Form 8-K.

Ambac Financial Group, Inc., headquartered in New York City, is a holding company whose affiliates provide financial guarantees and financial services to clients in both the public and private sectors around the world. Ambac's principal operating subsidiary, Ambac Assurance Corporation, a leading guarantor of public finance and structured finance obligations, has earned triple-A ratings from Moody's Investors Service, Inc. and Standard & Poor's Ratings Services; and a double-A rating from Fitch, Inc. Moody's has placed Ambac's triple-A rating on review for possible downgrade. Standard & Poor's has placed Ambac's triple-A rating on "credit watch negative." Fitch has placed Ambac's double-A rating on "rating watch negative." Ambac Financial Group, Inc. common stock is listed on the New York Stock Exchange (ticker symbol ABK).