Bob Lambert, ex-deputy chief of a covert Met unit, says in an exclusive interview that "at no time" was his team involved with trying to smear the family of the murdered teenager, Stephen Lawrence.

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The former second-in-command of the undercover Special Demonstration Squad (SDS) said that he had "always had the greatest empathy" for the teenager's parents, Doreen and Neville Lawrence.

He denied allegations that the unit, part of the Met's Special Branch, had been asked to find "dirt" that could be used against members of the Lawrence family and friends shortly after Stephen's murder in April 1993.

The allegations were made by the former undercover officer turned whistleblower, Peter Francis.

Mr Francis said that as a member of the SDS he was told to "get any information on what was happening in the Stephen Lawrence campaign".

'No smear campaign'

Now a lecturer in terrorism studies at the University of St Andrews, Mr Lambert became operations manager in the elite undercover unit, it is understood, in November 1993. It is thought he took on this managerial role a couple of months after Peter Francis had been deployed undercover into a group called Youth Against Racism.

Mr Lambert said: "I really do want to reassure them that at no time in my tenure as an SDS manager - which is from November 1993 until when I left in 1998, which was roundabout the time of the Stephen Lawrence Inquiry - at no time was the Special Demonstration Squad concerned in smearing their family or their campaign."

There was no smear campaign. Bob Lambert

Mr Lambert, however, does concede that it is possible, as alleged by Peter Francis, that details on people who visited the family home may have been passed to Special Branch.

Mr Francis has claimed that a family liaison officer passed to special branch the names of all those who entered the family home during a period following Stephen's murder. There is no suggestion any family liaison officer knew how such information would be used.

Bob Lambert, when asked if he or anyone in Special Branch had received information about visitors to the Lawrence family home, told Channel 4 News "not to my direct knowledge, but I wouldn't rule it out."

Peter Francis has also stated that the police wanted to discredit Duwayne Brooks, the friend of Stephen Lawrence who witnessed his murder.

Bob Lambert says he is not aware of that having happened.

Mr Lambert is not in a position to answer all of the claims, not least because he joined the unit after Peter Francis was deployed.

But he is unequivocal when it comes to the wider allegation that his unit was involved in trying to undermine the Lawrence family's campaign: "There was no smear campaign."

Full inquiry will 'get to truth'

Peter Francis told Dispatches, which investigated the claims jointly with the Guardian, that throughout his deployment "there was almost constant pressure on me personally to find out anything I could that would discredit these campaigns."

Mr Francis has since told Channel 4 News that he stands by what he said and would be willing to say it all under oath: "It does not surprise me that Mr Lambert has responded in this way to me becoming a whistleblower and telling the public what really happened in the SDS.

"I have complete faith that a full, independent inquiry will get to the truth."

'Deeply concerned'

David Cameron said that he was "deeply concerned" by the allegations and called for an investigation.

On Friday, Ms Lawrence met the Metropolitan Police commissioner Bernard Hogan-Howe, to discuss the claims. "It will take a while to gain back trust again," she said after the meeting.

Mr Hogan-Howe described the meeting with Mrs Lawrence and her son Stuart as "constructive", adding: "These are serious allegations and I understand why the Lawrence family want answers quickly".

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