Boris Johnson faces a mounting Tory backlash over his handling of the Chris Pincher row after he apparently forgot being told about an official complaint about the former minister’s “inappropriate” behaviour.

The Prime Minister’s spokesman confirmed that Mr Johnson was briefed on the complaint by officials at the Foreign Office in 2019, a “number of months” after it took place.

The spokesman said the complaint against Mr Pincher – who was Europe minister at the time – was upheld although it did not lead to formal disciplinary action.

Deputy Prime Minister Dominic Raab, the then foreign secretary, gave Mr Pincher a dressing down over his “inappropriate” conduct “in no uncertain terms” and the Cabinet Office’s propriety and ethics team was also involved.

No 10 had previously claimed Mr Johnson had not been aware of any “specific allegations”, after Mr Pincher’s dramatic resignation last week as deputy chief whip following claims he groped two men at a private members’ club.

“At the time last week that was the Prime Minister’s view.

“You will appreciate it takes some time to establish he was briefed, albeit we don’t think in formal briefing on this,” the spokesman said.

“This dates back a number of years.

“On Friday, it was our belief that he was not informed about that specific incident.”

By Monday that line had evolved to acknowledge the Prime Minister was aware of “allegations that were either resolved or did not progress to a formal complaint”.

Cabinet Office Minister Michael Ellis told MPs that Mr Johnson had been made aware of the Foreign Office investigation but “no issue” arose about Mr Pincher remaining as a minister because appropriate action was taken.

“Last week, when fresh allegations arose, the Prime Minister did not immediately recall the conversation in late 2019 about this incident,” Mr Ellis said.

“As soon as he was reminded, the No 10 press office corrected their public lines.”

The admission that Mr Johnson forgot about the earlier complaint came after the former top civil servant at the Foreign Office, Lord McDonald, said the original No 10 account was “not true” and the Prime Minister had been briefed “in person”.

For Labour, deputy leader Angela Rayner said the latest disclosures revealed an “ethical vacuum” at the heart of Downing Street.

“The Prime Minister was personally informed about these allegations and yet he was either negligent or complicit,” she said.

As well as the Foreign Office complaint, Mr Johnson was also informed about another allegation against Mr Pincher at the time of the reshuffle when he was made deputy chief whip in February 2022, although this claim was “not taken forward”, according to No 10.

A third incident, the one which triggered Mr Pincher’s resignation, is now being examined by Parliament’s Independent Complaints and Grievance Scheme (ICGS).

In the Commons, the atmosphere among Tory MPs was mutinous with critics lining up to condemn the handling of the situation by Mr Johnson’s No 10 operation.

William Wragg, the Conservative MP who chairs the Commons Public Administration and Constitutional Affairs Committee, said ministers should consider how long they were prepared to carry on supporting the Government.

“I would ask them to consider the common sense of decency that I know the vast, vast majority of them have and ask themselves if they can any longer tolerate being part of a Government which, for better or worse, is widely regarded of having lost its sense of direction,” he told the House.

Sir Bernard Jenkin, chairman of the Liaison Committee which will question Mr Johnson on Wednesday, demanded to know why those with “the wrong attitudes and the wrong behaviours” are promoted by their leaders.

Jackie Doyle-Price, a former whip, insisted the whiff of rumours and historical incidents surrounding Mr Pincher should have been enough to tell the Prime Minister the appointment as deputy chief whip was not “wise”.

She also called for a “complete reset of standards” and “a complete reboot of the Ministerial Code”.

Tory MP Peter Bone’s supportive intervention in the Commons chamber stood out so much that even Speaker Sir Lindsay Hoyle remarked that he was a “lone batter” for the Government.

In his letter to the parliamentary standards commissioner, Lord McDonald said that a group of officials had complained to him about Mr Pincher’s conduct along similar lines to his alleged behaviour at the Carlton Club.

Following an investigation, the complaint was upheld, Mr Pincher apologised and promised there would be no repeat of his behaviour.

“Mr Johnson was briefed in person about the initiation and outcome of the investigation,” Lord McDonald wrote.

“There was a ‘formal complaint’. Allegations were ‘resolved’ only in the sense that the investigation was completed; Mr Pincher was not exonerated.

“To characterise the allegations as ‘unsubstantiated’ is therefore wrong.”

Such an intervention is rare for a retired mandarin but he said he was acting “out of my duty towards the victims”.

“Mr Pincher deceived me and others in 2019. He cannot be allowed to use the confidentiality of the process three years ago to pursue his predatory behaviour in other contexts,” he wrote.