Rishi Sunak was told Gavin Williamson faced bullying claims before cabinet appointment

Sir Gavin Williamson allegedly sent abusive text messages to the party’s former chief whip

Sir Gavin Williamson and Wendy Morton. PA

Britain’s new prime minister knew a colleague was under investigation for bullying when he brought him back into government.

Rishi Sunak was told about the complaint against Sir Gavin Williamson days before he appointed him to the cabinet, said former chairman of the Conservative Party, Sir Jake Berry.

Sir Gavin allegedly sent abusive text messages to the party’s former chief whip, Wendy Morton, complaining he and others had been excluded from Queen Elizabeth II’s funeral for political reasons.

In the messages, Sir Gavin started by saying: “There is a price for everything”. He said Ms Morton's conduct was “absolutely disgusting” and went on to use multiple expletives.

Sir Gavin is facing an investigation over the series of alleged abusive and threatening messages.

Mr Sunak promised to serve with “integrity and humility” when he succeeded Liz Truss in late October.

But this is the second complaint he has faced about a cabinet appointment in less than two weeks, after he brought Ms Braverman back into government six days after she was found to have breached the ministerial code, forcing her resignation under Ms Truss.

Sir Jake said he informed the prime minister and his incoming chief of staff the same day, the day before Mr Sunak entered No 10, that Ms Morton was submitting a complaint about the messages, The Times reported.

Oliver Dowden, the chancellor of the Duchy of Lancaster, who has been described as Mr Sunak’s “right-hand man”, has confirmed the prime minister was aware of the complaint when he appointed Sir Gavin a minister of state without portfolio.

Speaking on the BBC's Sunday with Laura Kuenssberg, Mr Dowden said: “It was not the case though that the prime minister saw the texts themselves.

“The complaint itself is ongoing and I don’t think it would be appropriate for me to prejudge that.”

He said it was not acceptable for Sir Gavin to have spoken to Ms Morton in that way, but the texts were sent “in the heat of the moment at a very difficult time”.

“Gavin accepts he shouldn’t have said these things and he regrets it,” Mr Dowden said. “We should all treat each other with respect and courtesy, and that was not the case there.”

In a separate interview on Sky News’s Sophy Ridge on Sunday, Mr Dowden said: “Of course the prime minister continues to have confidence in Gavin Williamson.”

Labour's shadow climate change secretary Ed Miliband warned against a “cover-up” or a “whitewash” over allegations relating to Sir Gavin.

He told Sky News: “These are incredibly serious issues and I think it really calls into question Rishi Sunak's judgment and the way he made decisions about his cabinet.

“We already know about the whole Suella Braverman issue: being reappointed six days after she resigned.

“It was very noticeable … that Oliver Dowden couldn't deny that Rishi Sunak knew about those issues to do with potential bullying against Wendy Morton, the chief whip, by Gavin Williamson and yet he reappointed him.

“What it says is that Rishi Sunak was making decisions simply in his own narrow short-term interest as far as the Conservative Party leadership was concerned, not the national interest, and there needs to be an urgent independent investigation into exactly what happened. We can't have a cover-up, we can't have a whitewash here.

“What did Rishi Sunak know? When did he know it? What did Gavin Williamson do and what are the implications of that?”