SIR GAVIN Williamson must be stripped of his knighthood if he is found guilty of bullying, the Liberal Democrats said.

LibDem chief whip Wendy Chamberlain, the MP for North East Fife, said the honours system would be “brought into disrepute” otherwise.

Sir Gavin quit as a minister on Tuesday, just a fortnight after Rishi Sunak promoted him to the cabinet despite knowing an official complaint had been lodged against him at Tory HQ.

Former chief whip Wendy Morton complained about expletive-laden messages Sir Gavin sent accusing her of “rigging” the guest list at the Queen’s funeral to exclude him.

Further claims of bullying then emerged from MPs and a civil servant who said that in his previous role as defence secretary, Sir Gavin told him to slit his own throat.

As well as Tory HQ, Sir Gavin is also facing an investigation by the Cabinet Office’s ethics team and by Westminster’s independent complaints and grievance scheme.

Ms Chamberlain has now written to the Cabinet Office’s Forfeiture Committee, which can decide to withdraw honours for criminal convictions and unacceptable conduct.

She also called on Mr Sunak, who accepted Sir Gavin’s resignation “with great sadness”, to confirm he would back Sir Gavin losing his knighthood if found guilty of bullying. 

She said: “The complaints being made about Gavin Williamson are extremely serious and suggest a bullying culture at the very top of the Conservative Party. 

“If these complaints are upheld he should be stripped of his knighthood, or else the whole honours system risks being brought into disrepute.

“Rishi Sunak appointed Williamson to Cabinet despite knowing of serious complaints about his behaviour. Since then he sat on his hands for days instead of taking action.

“The very least Sunak could do now is confirm he would support taking Williamson’s knighthood away if the investigations into his behaviour find him guilty.”

In her letter to committee chair Sir Chris Wormald, Ms Chamberlain “several extremely concerning allegations” had been made recently about Sir Gavin’s past behaviour. 

“These include complaints made by former Chief Whip Wendy Morton about bullying text messages, and a senior civil servant who alleges that Mr Williamson told them to ‘slit your throat’ and has since made a formal complaint to Parliament’s bullying watchdog. 

“On top of this, former Deputy Chief Whip Anne Milton has claimed that Mr Williamson once boasted of ‘owning’ a Conservative MP after offering him financial help.

“All of these complaints suggest a pattern of behaviour that is not in keeping with the high standards expected of recipients of honours, who as stated by the Forfeiture Committee should remain good citizens and role models. 

“The Forfeiture Committee states that it will consider withdrawing honours from individuals if their behaviour results in censure by a regulatory or a professional body, or any other behaviour that is deemed to bring the honours system into disrepute.

“I therefore would urge you to consider withdrawing Gavin Williamson’s knighthood if the serious allegations made against him are upheld in the numerous investigations currently being undertaken.”

The Prime Minister’s press secretary said it would be a question for the Forfeiture Committee whether Sir Gavin should be stripped of his knighthood.

Asked if the PM thought Sir Gavin should lose the title, she said: “I believe there is a formal process for that called the Forfeiture Committee. And that would be a decision for them.”

She also confirmed SIr Gavin sought a face-to-face meeting with Mr Sunak on Tuesday evening before offering his resignation.

Pressed on whether Mrr Sunak might have known the nature of Ms Morton’s complaint against Sir Gavin, if not the details, she added: “It wouldn’t be right for me to comment on complaints processes because they are rightly kept confidential.”