'Wholly common-sensical' for police to arrest Andrew Mitchell says mischievous Boris Johnson

Boris Johnson fuelled the row over Andrew Mitchell's Downing Street tirade today by suggesting the policeman concerned might have been sensible to arrest the Chief Whip.

In a mischievous intervention, the London Mayor said the idea that Mr Mitchell could have been detained for his outburst was "wholly commonsensical". It also emerged last night that David Cameron decided to back Mr Mitchell after his Chief Whip looked him "in the eye" and denied he had called Downing Street policemen "plebs".

Speaking during his visit to the UN last night, the Prime Minister said: "The Chief Whip has a made a clear and public apology." Noting that the police have not pressed charges, he added: "That is where things should rest."

But the political row caused by the altercation showed no sign of dying down with reports that Mr Mitchell requested to be let through the main Downing Street gates again – just 12 hours after the original confrontation.

Mr Johnson's comments came as Labour accused the Prime Minister of presiding over a "cover-up" for failing to order an official inquiry into what happened during the altercation.

The Police Superintendents Association added that Mr Mitchell's assertion that he had not used the words attributed to him challenged the "integrity" of the officer concerned which, it said, was "a really serious matter".

Mr Johnson said he accepted Mr Mitchell's apology but added that the incident "underscored" how wrong it was for anyone to abuse a police officer. "If I read the papers correctly there was a proposal to arrest Mr Mitchell for what he said," Mr Johnson told reporters. "That seems to be wholly commonsensical. The Public Order Act does allow for police officers' discretion in this matter. They've obviously decided not to go ahead with it. But it shows the gravity of this offence."

A police log leaked yesterday revealed that the officer threatened to arrest Mr Mitchell for his abusive language. The officer wrote: "I warned Mr Mitchell that he should not swear, and if he continued to do so I would have no option but to arrest him under the Public Order Act, saying: 'Please don't swear at me, sir. If you continue to, I will have no option but to arrest you'. Mr Mitchell was then silent and left saying, 'You haven't heard the last of this' as he cycled off."

Shadow Home Secretary Yvette Cooper said it was essential to establish who was telling the truth about the claim Mr Mitchell referred to the police as "plebs". "It now looks like there is a cover-up going on," she said. "You read these reports and you have got a cabinet minister not just swearing at police but sneering at them, calling them plebs.

"I don't think the Prime Minister can just dismiss this and try and sweep this under the carpet."

Irene Curtis, head of the Police Superintendents' Association, said the incident had "gone beyond the words that were used" and was "an issue of integrity for the officer". "By challenging the officer's version of events he is actually challenging the officer's integrity."

But Sir Hugh Orde, president of the Association of Chief Police Officers, backed Met Commissioner Bernard Hogan-Howe's view that there was no need for further action. "There are far more important issues in policing that need to be dealt with and we need to move on from it," he said. A Home Office Minister, James Brokenshire, said it was possible Mr Mitchell and the officer genuinely had different recollections of what happened. "I have no reason to doubt the recollections of either Andrew Mitchell or the police officer concerned," he told Sky News.

A real pleb: Mitchell's roots

Andrew Mitchell is known to proudly proclaim that he is the fourth generation of his family to serve as an MP. However, his mother's roots are rather more… plebeian.

Research by the family history website Findmypast reveals that he has a good chunk of East End, London working-class stock in him. His grandmother on his mother's side, Ellen Haysey, was born in Forest Gate and is listed on the 1911 census as a domestic servant. The 16-year-old worked for a family in Woodford Green, Essex. His great grandmother, also called Ellen, is listed in the 1901 census as a 37-year-old charlady from Bow.