Plebgate: David Cameron knew Andrew Mitchell evidence was suspect three months ago

PM refused to press issue with Met police even though it could have saved Chief Whip’s job, as details of secret talks emerge

David Cameron has known for almost three months that at least one member of his own élite protection unit may have fabricated parts of the Downing Street police log about the confrontation with Andrew Mitchell, The Independent understands.

Weeks before the former Chief Whip fell on his sword, the Prime Minister was alerted to vital inconsistencies between CCTV footage of the altercation and a police officer’s log of the incident leaked to the media.

The evidence was enough to persuade Mr Cameron to stand by Mr Mitchell despite the public clamour for his resignation.

But, crucially, the Prime Minister decided not to press the matter with the Metropolitan Police – fearing that it would poison relations with the elite group of policemen who guard senior politicians.

Speaking today on a visit to Afghanistan Mr Cameron said he took “full responsibility” for the Downing Street investigation.

He also revealed that he had met Mr Mitchell the night before a Channel 4 news and Dispatches investigation broadcast the CCTV evidence which suggested the police account of the altercation was flawed.

“I saw him in Number 10. I spoke to him and my office has been in contact with him, as you would expect, fairly regularly,” he said.

Asked what frame of mind Mr Mitchell was in, Mr Cameron replied: “I thought his mood was very calm and rational given what were very disturbing revelations.”

Mr Cameron did not rule out a return to Government by Mr Mitchell in the future.

“One step at a time. Let's get to the truth about what happened,” he said.

“But I think it has been an extraordinary development, frankly, to find a police officer apparently posing as a member of the public, pretending to have been outside Downing Street at the time and then trying to blacken the name of a Cabinet minister.”

The Independent has pieced together the chronology of events following the 19 September altercation in Downing Street – and Mr Cameron’s significant behind-the-scenes role in the affair.

When Mr Cameron was first alerted to an email from a supposed member of the public who witnessed the now infamous “Plebgate” altercation, he called in Mr Mitchell with the intention not of asking him to resign – but of sacking him on the spot.

But such were Mr Mitchell’s denials that the incident had been anything like that described in the email or the accounts given by police that the Prime Minister agreed to stay the execution.

Instead, he agreed that Sue Gray, Downing Street’s director of propriety and ethics, would work under the Cabinet Secretary, Sir Jeremy Heywood, independently to examine the Downing Street and Foreign Office CCTV logs to see whether they could substantiate the accounts of either Mr Mitchell or the policemen.

What Ms Gray and Sir Jeremy found when they watched the tapes not only appeared to back Mr Mitchell’s version of events, but raised the prospect that the officers involved had embellished a key part of their account. Far from there being members of the public looking on “shocked” at the incident, the street outside the gates was almost deserted – with just a couple of individuals passing but not lingering.

The Independent understands Ms Gray and Sir Jeremy alerted Mr Cameron to what they had found – and he himself watched the tapes.

But a decision was taken by the Prime Minister not to pursue the matter with police commanders or make the CCTV footage public. Instead he agreed a compromise: he would back Mr Mitchell to stay in his job but would allow the discrepancies the footage revealed to go unchallenged.

The revelations raise questions for the Met Commissioner, Bernard Hogan-Howe, who backed the officers involved in the confrontation following the arrest.

Scotland Yard has launched an inquiry with 30 officers looking into the leaks of the official police log to The Daily Telegraph and the possibility of a wider criminal conspiracy to bring down the former Chief Whip.

Responding to the new revelations yesterday, the Prime Minister said allegations that a police officer posed as a member of the public and fabricated evidence to damage the then-Chief Whip were “extraordinary”.

Mr Cameron, who is visiting Afghanistan, was asked in interviews whether Mr Mitchell could make a comeback. “One step at a time. Let’s get to the truth about what happened,” he said.

“But I think it has been an extraordinary development, frankly, to find a police officer apparently posing as a member of the public, pretending to have been outside Downing Street at the time and then trying to blacken the name of a cabinet minister.”

Keith Vaz, the chair of the Home Affairs Select Committee, questioned whether the inquiry should be carried out by one of the police watchdogs. In his letter to Mr Hogan-Howe, he asked why the leaked log appeared to be in conflict with CCTV evidence. Scotland Yard did not dispute the authenticity of the leaked log yesterday.

The man arrested yesterday was held on suspicion of “intentionally encouraging or assisting the commission of an indictable offence on or around 14 December” and bailed until January. Scotland Yard declined to go into further detail but 14 December was a day after new material on “Plebgate” was passed to the force, and one day before the arrest of an officer from the diplomatic protection group on suspicion of misconduct in public office.

That arrest related to the sending of an email to one of Mr Mitchell’s deputies, purportedly from a member of the public, but who was in fact a serving Met police officer.