LONDON (Standard&Poor's) Nov. 22, 2007--Standard&Poor's Ratings Services said today it assigned its preliminary 'AAA' rating to the debt to be issued by U.K.-based special purpose vehicle (SPV) BY Chelmer PLC (the Issuer or ProjectCo). The rating reflects the unconditional and irrevocable payment guarantee of scheduled interest and principal provided by Ambac Assurance U.K. Ltd. (AAA/Stable/--). The preliminary underlying rating (SPUR) on the debt is 'BBB', with a stable outlook. The proposed debt consists of £189.2 million in senior secured bonds due 2043 (including £30 million of variation bonds). The senior secured bonds have been assigned a preliminary recovery rating of '2', indicating our expectation of substantial recovery of principal (70%-90%) in the event of a payment