The Metropolitan Police was under mounting political pressure last night to investigate fresh evidence suggesting the Stephen Lawrence murder inquiry was derailed by police corruption.
The Independent understands that Stephen's family will press Scotland Yard to investigate new claims of corruption involving a key member of the team which bungled the initial 1993 murder investigation.
The police and the Crown Prosecution Service are due to meet Doreen Lawrence on Friday to discuss their next steps following the convictions in January of two of her son's killers, Gary Dobson and David Norris. Mrs Lawrence will also ask for a new inquiry into corruption within the original inquiry team.
Her appeal follows an investigation by The Independent, which uncovered new accusations of criminality against former Detective Sergeant John Davidson, who played a leading role in the original hunt for the racist killers.
The allegations in police files were withheld from the Lawrence family and appear not to have been passed in full to the Macpherson inquiry into the botched murder investigation.
The files claimed Det Sgt Davidson dealt "in all aspects of criminality", while a police supergrass alleged that the former sergeant admitted officers had a corrupt relationship with Clifford Norris, the father of David Norris.
The disclosures provoked alarm at Westminster, with demands for a new inquiry into corruption. There was also anger at the investigation by the Independent Police Complaints Commission (IPCC) into such serious charges.
Friday's meeting was scheduled following the conviction of Dobson and Norris, for 15 years and 14 years, respectively. They both plan to appeal.
Scotland Yard said last night it had no plans to investigate further.
But the former Home Secretary Jack Straw, who set up the Macpherson inquiry, said: "It was certainly the case that there were very high suspicions that serious police corruption had been involved in the failure of the initial police investigation into Stephen Lawrence's killing.
"As far as these allegations are concerned, I think the Metropolitan Police Service needs now to explain why they weren't disclosed to the Macpherson inquiry, if necessary in confidence."
Keith Vaz, the chairman of the Commons Home Affairs Select Committee, said: "These new disclosures are very concerning. Not only do they add to the questions over police conduct in the original Stephen Lawrence investigation and subsequent inquiries, but highlight a complete lack of action against corruption. These allegations must now be fully investigated." Clive Efford, the Labour MP for Eltham, where Stephen was murdered, said: "The position of the Metropolitan Police is unsustainable. We need full disclosure of documents from it and someone independent to investigate. Given the record of the IPCC, they might not be the right people. Perhaps Sir William Macpherson should be asked to come out of retirement and take a fresh look at all the evidence."
The Tory MP Ben Gummer, who has pursued the corruption allegations in parliamentary questions, said: "Anyone reading the original IPCC report and the new investigation by The Independent can't fail to wonder why the IPCC hasn't reopened this investigation already. They need to give far fuller answers than they have so far to the serious questions being put to them."
All three main candidates for the London mayoralty expressed their alarm. A spokesman for Boris Johnson, the Mayor, said: "Any new evidence of police corruption in relation to the Stephen Lawrence murder investigation would be taken very seriously. We encourage anyone who has any evidence to hand it over to the police."
Ken Livingstone, his Labour challenger, said: "These new revelations are deeply disturbing and must be fully investigated."
The Liberal Democrat candidate, Brian Paddick, a former senior Met officer, said he had been told that Mr Davidson had recently offered to be interviewed by the police over his role in the Lawrence case, but that the police did not take up the offer. He claimed: "There is prima facie evidence here that the police failed to properly investigate the very serious allegations that the actions of a corrupt police officer could have derailed the initial Stephen Lawrence investigation."