SCOTLAND Yard is fighting an extraordinary legal battle to withhold 123-year-old secret files that experts believe could finally provide the identity of Jack the Ripper.

Four thick ledgers compiled by Special Branch officers have been kept under lock and key since the Whitechapel murders in 1888.

Will Jack the Ripper's identity be revealed?

Trevor Marriott, a Ripper investigator and former murder squad detective, has spent three years attempting to obtain uncensored versions of the documents.

But he has been repeatedly refused because the ledgers contain the identities of police informants - and the Metropolitan Police insist that revealing the information could compromise the gathering of information from ''supergrasses'' and other modern-day informants.