Intelligence that linked a suspected corrupt police officer on the Stephen Lawrence murder investigation to the gangster father of one of the prime suspects was apparently suppressed to protect the then Metropolitan Police Commissioner.

A memo written in 2000 by a Met Police lawyer suggests the force suppressed information that John Davidson, a detective sergeant on the original botched investigation, was connected to the father of David Norris, one of the racist gang who stabbed Stephen Lawrence to death in 1993.

The file goes on to warn a police officer who was preparing to leak information on the Lawrence case to a journalist that “disclosures relevant to DS Davidson’s contact with the Norris family could have an adverse effect on the Commissioner’s position in the on-going High Court action by Mr and Mrs Lawrence”.

Download the new Independent Premium app Sharing the full story, not just the headlines

At the time, Doreen and Neville Lawrence were suing Scotland Yard for misfeasance in public office under the then Commissioner Lord Stevens following years of appalling police treatment following the death of their son.

The memo from David Hamilton of the Met’s directorate of legal services corroborates incendiary claims by police “supergrass” Neil Putnam. He has always maintained he told the Met in 1998 of the alleged corrupt relationship between Davidson and Clifford Norris right in the middle of a judicial inquiry into the appalling case.

A review of the Lawrence murder found that full details of Mr Putnam’s evidence was withheld from Sir William Macpherson during his landmark inquiry. The Home Secretary described this as “deeply troubling” and prompted accusations of a “cover-up”.

Sir Bernard Hogan-Howe, the current Metropolitan Police Commissioner, was thrown into the centre of the storm after Mark Ellison QC concluded in his review that Scotland Yard may not have told him the truth about Davidson’s links to another notorious unsolved case, the murder of Daniel Morgan, prompting Mrs May to order yet another judge-led public inquiry into corruption inside Britain’s biggest police force.

The new memo on the links between Davidson and Clifford Norris was buried in the detail of the Ellison review, which also found that the Met inexplicably shredded four years’ worth of relevant information to the Lawrence case in 2003 when Lord Stevens was Commissioner.

In the summer of 2000, officers including Detective Chief Superintendent John Yates were preparing to leak sensitive information on police corruption to a former BBC journalist Graeme McLagan.

Yates, who rose to become an assistant commissioner before resigning in the wake of the phone-hacking scandal, told the Ellison review that he believed the decision to pass on the material was taken by Lord Stevens.

Daily coronavirus briefing No hype, just the advice and analysis you need Enter your email address Continue Continue Please enter an email address Email address is invalid Fill out this field Email address is invalid Email already exists. Log in to update your newsletter preferences Register with your social account or click here to log in I would like to receive morning headlines Monday - Friday plus breaking news alerts by email Update newsletter preferences

Before the information was sent to McLagan, Mr Hamilton in the Met’s legal department wrote to a junior officer dealing with the matter on 14 August 2000 warning of the sensitivities around Davidson.

“If confidence were to be breached, consideration would have to be given to the effect on any ongoing trials in this series should any of the contents of the complaints history be leaked.

“Disclosures relevant to DS Davidson’s contact with the Norris family could have an adverse effect on the Commissioner’s position in the on-going High Court action by Mr and Mrs Lawrence. Part of their claim is based on misfeasance in public office and alleges wrongdoing in relation to dealings between police and the Norris family.”

Crucially, the Ellison review was also told by Martin Polaine, a former CPS lawyer, that he recalled hearing of Mr Putnam’s allegation about Davidson and Clifford Norris in July 1998 – long before Lord Stevens wrote to the Macpherson Inquiry, releasing minimal information about the officer’s alleged corruption. DS Davidson denies all the allegations.

Meanwhile, the Ellison review also uncovered Met intelligence that Davidson was linked to a private investigation firm Mayfayre Associates, run by two former Scotland Yard police officers, Alec Leighton and Keith Hunter.

In 2012, Mr Hunter was arrested and is currently on bail over the alleged bribery of police officers in relation to an investigation into James Ibori, a Nigerian politician convicted of fraud and money-laundering. He denies any wrongdoing.

* John Yates has contacted The Independent to say that he wants to make it clear that he had no involvement in the decision to co-operate with Mr McLagan and did not pass any information to him. He objects to the word ‘leaked’ to describe the passing of, or giving access to information to Mr McLagan. The decision to cooperate with Mr McLagan in the writing of his book was an operational strategy agreed at the highest level.

He re-iterates what he told the Ellison Review: he believes that this was a decision authorised by the then Deputy Commissioner, Lord Stevens.