Boris Johnson under pressure over Chris Pincher claims

However, according to his former chief aide, Dominic Cummings, the Tory leader jokingly referred to the MP as "Pincher by name, pincher by nature".

Mr Pincher quit as the party’s deputy chief whip on Thursday, saying he had "drunk far too much" the previous evening. He was later accused of drunkenly groping two men. 

After initially hoping to draw a line under the incident, No 10 were then forced to suspend the MP the next day when one of the men lodged a complaint with the Parliamentary watchdog, the Independent Complaints and Grievances Scheme.

Conservative Staffers for Change, a group of young people working in parliament for MPs, told the Times that Mr Pincher’s “behaviour was an open secret in Westminster and it is disappointing that this was not addressed sooner.”

The group, whose leading members include Oliver Briscoe, the researcher for West Aberdeenshire and Kincardine MP Andrew Bowie, said they had “raised concerns about sexual misconduct with the chief whip” and were “disappointed not only by how long it took to remove the whip from Pincher, but also at the continued lack of clarity about what the PM knew.”

Over the weekend a further 13 claims of inappropriate behaviour by Mr Pincher emerged. 

He has denied the allegations.

Mr Pincher previously stood down from the whips' office in 2017 when he was accused of making an unwanted pass at former Olympic rower and Tory activist Alex Story.

He was later cleared of any breach of the Tory party's code of conduct.

Mr Pincher released a statement at the end of last week, saying he was seeking “professional medical support” and hoped to “return to my constituency duties as soon as possible."

Asked on BBC Radio 4’s Today programme why the Prime Minister had given Mr Pincher a job with responsibility for the behaviour of MPs, Mr Quince, a junior minister in the Department for Education said: “That is a question and one for the Prime Minister and not for me. I wasn’t in the room and not alive to the conversations.”

Asked about his own awareness of rumours about Mr Pincher, Mr Quince said: “There are a lot of rumours and gossip around Westminster… If I had a pound for every rumour that I’d heard about another MP, then I’d be a very wealthy man.”

Earlier, Mr Quince told Sky News he had “been given categorical assurance that the Prime Minister was not aware of any serious specific allegation with regards to the former deputy chief whip.”

Asked about the quote from Mr Cummings, the minister said the ex-adviser was “not someone who I give a huge amount of credibility to, given past experience.”

Labour Party chair Anneliese Dodds has written to the prime minister demanding to know what Downing Street knew of the allegations about his ally before his second appointment as a whip in February. 

"Only Boris Johnson could have looked at this guy's record and thought 'he deserves a promotion'," she said.

"This prime minister is clearly happy to sweep sexual misconduct under the carpet in order to save his own skin."

The call was echoed by Liberal Democrat chief whip Wendy Chamberlain. She said Mr Johsnon “must now be forced to reveal what he knew before making the appointment." 

Meanwhile, there are suggestions that this week’s elections for the executive of the 1922 Committee backbench group of MPs could lead to renewed calls for a confidence vote for the Prime Minister. 

Under the current rules, the Prime Minister should be safe for another year after narrowly winning last month's vote. 

But with 18 positions on the 1922 Committee’s executive up for grabs, that rule could soon change.

One proposal being put forward would see Mr Johnson face a second confidence vote if 25 per cent — 90 MPs — submitted letters to Sir Graham Brady, the committee chairman. 

“This is a unifying manifesto point,” one MP thinking of standing told The Times. “It unites those chomping at the bit to get him out and those who are reserved about rules changes.”