Theresa May, the Home Secretary, has ordered an inquiry into allegations that police corruption hampered the original investigation into the murder of Stephen Lawrence, following an investigation by The Independent.
Mrs May has over-ruled Scotland Yard, which said its own inquiries into the corruption claims found no new evidence that would warrant a further investigation.
The Home Secretary has spoken to Doreen Lawrence, mother of the black teenager killed in racist attack in Eltham, south London, in 1993, to tell her that a QC will now look into the allegations. The QC has not yet been chosen.
Whitehall sources said that, by opting for a lawyer rather than a judge, Mrs May was seeking short, sharp review of the evidence rather than an inquiry that would drag on for months or years.
Her decision is also seen in Whitehall as a setback for the Independent Police Complaints Commission, which found no new evidence or information to support the corruption claims.
A Home Office spokesman said today: "The Home Secretary has asked for a QC-led review of the work the Metropolitan Police has undertaken into investigating claims of corruption in the original Stephen Lawrence murder investigation.”
David Norris and Gary Dobson were convicted of the 1993 racist murder of the teenager in January this year - 19 years after the crime - and sentenced to life at the Old Bailey.
The review comes after Mr Lawrence's mother, Doreen, called for a fresh public inquiry after it was claimed the Metropolitan Police withheld paperwork from the Macpherson Inquiry.
The Met launched a review to examine the claims, while the Independent Police Complaints Commission reviewed its 2006 investigation into complaints following the broadcast that year of the BBC programme The Boys Who Killed Stephen Lawrence.
Officers from the Met's Directorate of Professional Standards (DPS) looked at thousands of documents, many dating from the 1980s, from Met Police archives and from government archives in Kew, and spoke to serving and retired officers as well as the junior counsel for the MPS at the inquiry.
The review found that no investigations, nor the inquiry, uncovered evidence of corruption or collusion which could have hampered or influenced the original or subsequent investigations.
It also found that the force disclosed all material relating to "adverse information" it had about three officers of concern, including those the claims surrounded.
There was no other material known to be held by the force which suggested that corruption or collusion impacted on the initial investigation into Mr Lawrence's murder, and there are no new allegations from the recent claims, the force said today.
Any allegations or suggestions had already been investigated by the Met and IPCC, it said.
Commander Peter Spindler, from the DPS, said: "At this stage there are no new allegations or evidence that would merit further investigation.
"However, should any new information arise relating to alleged corruption in the original investigation into Stephen's murder, it would be seriously considered."
The police watchdog said its review followed reports on allegations made by former Met Police officer Neil Putnam about the relationship between former Detective Sergeant John Davidson and Clifford Norris, David Norris's father.
But today the IPCC also said it found that no new information or evidence has been made available which would lead to a change in the conclusions reached by its original investigation into allegations made by the BBC documentary.
Read The Independent's investigation here: