Boris Johnson is facing calls to expel the former Tory deputy chief whip from the party after he dramatically quit following a drunken incident.

Chris Pincher, who was responsible for maintaining discipline among Conservative MPs, said he had “embarrassed myself and other people” after having had “far too much” to drink.

The Sun reported that he stood down after assaulting two fellow guests at the Carlton Club – a Tory Party private members’ club in London’s Piccadilly – on Wednesday evening.

The MP is alleged to have groped two fellow male guests. Several Tory MPs are believed to have complained to the whips’ office about his behaviour.

However the paper said he would continue to sit as a Tory MP as he was considered to have done the right thing by admitting wrongdoing and resigning.

It is the second time Mr Pincher has quit the whips office, having resigned as a junior whip in November 2017 following a complaint that he made an unwanted pass at the former Olympic rower and Conservative candidate Alex Story.

Labour said the most recent incident showed the party was “mired in sleaze and scandal” and questioned how Mr Pincher could still be allowed to take the Conservative whip given what had happened.

In May, the Tory MP for Tiverton and Honiton, Neil Parish, resigned his Commons seat altogether after he admitted watching pornography in the Commons chamber.

Labour deputy leader Angela Rayner said: “This latest episode shows how far standards in public life have been degraded on Boris Johnson’s watch.

Chris Pincher (right) and chief whip Chris Heaton-Harris leave Downing Street following their appointments Chris Pincher (right) and chief whip Chris Heaton-Harris leave Downing Street following their appointments (Aaron Chown/PA)

“Boris Johnson has serious questions to answer about why Chris Pincher was given this role in the first place and how he can remain a Conservative MP.

“The Conservative Party is so mired in sleaze and scandal that it is totally unable to tackle the challenges facing the British people.”

Liberal Democrat chief whip Wendy Chamberlain has said it is “difficult to see” how Chris Pincher can remain as an MP.

The former Tory deputy chief whip is facing allegations of assault on two fellow guests at a Conservative Party private members’ club.

Ms Chamberlain said: “Given the seriousness of these allegations, it’s difficult to see how Chris Pincher can continue as an MP.

“This sort of behaviour is completely unacceptable in Parliament or anywhere else.

“There now needs to be a full investigation and in the meantime Chris Pincher should have the Conservative whip withdrawn.”

She also said that the Prime Minister has “serious questions to answer” over his appointment.

In his resignation letter to the Prime Minister, Mr Pincher apologised for his behaviour, saying it had been “the honour of my life” to have served in the Government.

“Last night I drank far too much. I’ve embarrassed myself and other people which is the last thing I want to do and for that I apologise to you and to those concerned,” he said.

Prime Minister Boris Johnson boarding a plane as he leaves the Nato summit in MadridBoris Johnson, leaving the Nato summit in Madrid, is facing calls to expel Mr Pincher from the Tory Party (Stefan Rousseau/PA)

“I think the right thing to do in the circumstances is for me to resign as deputy chief whip. I owe it to you and the people I’ve caused upset to, to do this.

“I want to assure you that you will continue to have my full support from the back benches. It has been the honour of my life to have served in Her Majesty’s Government.”

Allowing Mr Pincher to keep the Tory whip shows Boris Johnson “doesn’t take allegations of sexual assault as seriously as the leader of a Government should”, a Conservative MP said.

The MP, who declined to be named, said: “Let’s not forget that Mr Pincher is the man who helped keep Boris Johnson in Downing Street earlier this year and was rewarded with one of the most sensitive jobs in Government.

“Number 10’s initial response – suggesting he’s done ‘the decent thing’ and allowing him to retain the whip – tells us that Boris Johnson doesn’t take allegations of sexual assault as seriously as the leader of a Government should and is the latest demonstration of why he is unfit to be Prime Minister.

“The standards of behaviour expected in an organisation are set by the person who leads it.”

Mr Pincher's departure in such dramatic circumstances is a further blow for the Prime Minister who has been beset with allegations of misconduct over lockdown parties in Downing Street.

The Tamworth MP was appointed alongside chief whip Chris Heaton-Harris last February to shore up support for the Prime Minister amid growing unrest among Tory MPs over the “partygate” disclosures.

Having referred himself to both the police and the Conservative Party complaints procedure following the 2017 incident with Alex Story, he was brought back by Theresa May as deputy chief whip in January 2018.

When Mr Johnson became Prime Minister in July 2019, he was moved to the Foreign Office as minister for Europe and the Americas before returning to the whips office for a third time.

His departure comes just days after Oliver Dowden quit as party co-chairman in the wake of the Wakefield and Tiverton and Honiton by-election losses.

It leaves Mr Johnson, who returned from the Nato summit on Thursday after nine days out of the country, with another headache with two crucial roles to fill.