Conservative MP Andrew Mitchell, who faced his own well-documented row with police officers, said: “Damian’s admission to a breach of the rules were completely dwarfed by the dreadful behaviour of the police.”

Mr Green resigned from the Cabinet last week after admitting he had made misleading statements suggesting he had no knowledge of the thousands of pornographic images on his parliamentary computer, uncovered by police during an unrelated raid in 2008.

While he insists he did not download or view the images discovered on a shared computer, he had been told of their existence by lawyers in 2013.

Earlier this month retired detective Neil Lewis, who took part in the 2008 raid, told the BBC that the images not only existed, but had been viewed extensively.

Sutton Coldfield MP Mr Mitchell said: “What the police did looks suspiciously like a vendetta where after nine years they finally got him, regardless of the justice of the case.

Damian has been accused of being a dirty old man, pornographer and a liar. He has daughters, he has a wife, and none of this has been proven.

“People may not particularly care about the fate of a politician but if the police can do it to him, as number two in the Cabinet, they can do it to anyone they choose.”

Mr Mitchell had his own battle with the police after an officer said he called him a “pleb” as he rode through the House of Commons gates on his bicycle. It later emerged that another officer fabricated an account in which a witness claimed to have heard Mr Mitchell use the word.

Nevertheless, Mr Mitchell lost a later libel case. It came out later that seven officers had committed misconduct including leaks to the press, with one boasting she could “topple” a government.

Last night ex-detective chief inspector Chris Phillips suggested Mr Green was collateral damage in a campaign to embarrass the Prime Minister.

“When I joined the police in 1981, Thatcher was in power and I’d say 85 per cent of all police officers supported the Conservative government,” he said.

“Now I think you’d struggle to find any police officers that privately support Theresa May.”