Cabinet Secretary ordered to explain why he failed to uncover 'Plebgate' truth

Sir Jeremy Heywood had been asked by the Prime Minister to investigate the confrontation fully

Sir Jeremy Heywood told David Cameron is was not possible to determine what happened from the CCTV footage (PA)

Britain’s most senior civil servant will be cross-examined by MPs tomorrow over whether he failed to get to the truth of the “Plebgate” affair that led to Andrew Mitchell’s resignation as Chief Whip.

In an unusual move, the Cabinet Secretary, Sir Jeremy Heywood, has been summoned before a parliamentary committee examining the storm that ended with Mr Mitchell being forced out of office.

The Independent revealed in December that David Cameron had known for almost three months that the evidence against Andrew Mitchell evidence was suspect – but did not press the issue with police for fear of poisoning relations with them.

Mr Mitchell admits swearing in the presence of officers who refused to let him wheel his bicycle out of Downing Street’s main gates, but has consistently denied using most of the language attributed to him, including the politically toxic insult “pleb”.

Mr Mitchell quit the Government after a month of pressure, but CCTV footage subsequently released has cast doubt on the version of events recorded in the official police log of the incident.

Thirty detectives are investigating whether there was a conspiracy against the minister.

A police officer and a relative have been arrested and statements have been taken from 800 officers in the diplomatic protection group. A report is due to be sent to the Crown Prosecution Service within weeks.

Much attention has focused on the role of Sir Jeremy who was asked by David Cameron to investigate the claims against Mr Mitchell when they were first reported last September.

The Cabinet Secretary viewed the CCTV film which seems to back Mr Mitchell’s version of events.

It apparently contradicts claims in the police log that members of the public looked on “shocked” at the incident, showing just two individuals passing the Downing Street gates but not lingering to look up the street.

Sir Jeremy reported back to Mr Cameron that it was impossible to ascertain exactly what had happened and the Prime Minister decided to support his embattled Chief Whip without releasing the footage. The Cabinet Secretary has been called before the Commons Public Administration Select Committee to detail how thoroughly he investigated the accusations.

Sir Bernard Hogan Howe, the Metropolitan Police Commissioner, today condemned public statements made by the Police Federation following the initial allegations against Mr Mitchell. The organisation, which represents rank-and-file officers, ran a vigorous campaign against the minister, with local branches organising protests at the Conservative party conference at which members appeared wearing “PC Pleb” T-shirts.

Sir Bernard told the Commons Home Affairs Select Committee: “My concern would be from some of the public statements from the Federation’s representatives is they got explicitly involved with asking for the resignation of a Government member and for me that is too much. “That’s a decision for the Government to make or the Prime Minister to make – and not for police officers to get involved in.”