David Davis, the man who has lead the way in the Brexit negotiations for Britain, is “threatening” to resign should the Prime Minister’s number two be sacked over pornography that was found on a computer in his Parliamentary office in 2008, a number of reports have claimed.

Sources said the Brexit Secretary had “put his cloak around” the embattled Mr Green in an effort to toughen Mrs May’s resolve to defend her deputy.

A mutual friend of Mr Davis and Mr Green told the Evening Standard: “David would find it quite difficult to stay in his job and not resign if Damian was pushed out because of anything related to what happened 10 years ago.”

A separate source close to Mr Davis said: "It’s right that allegations of misconduct towards individuals are properly investigated, but police officers have a duty of confidentiality which should be upheld."

The threat comes after a former Scotland Yard detective who seized a computer from Mr Green’s office in a police raid nine years ago said he had “absolutely no doubt whatsoever” the Tory MP had accessed pornographic images on it.

Neil Lewis, the man who examined Mr Green’s Parliamentary computer, said it would be “ridiculous to suggest that anybody else could have done it”.

Mr Green has denied downloading or watching porn on the work computer as well as allegations of inappropriate behaviour towards a young female activist which are currently the subject of a Cabinet Office investigation.

A spokesman for the First Secretary of State said: "It would be inappropriate for Mr Green to comment on these allegations while the Cabinet Office investigation is ongoing; however, from the outset he has been very clear that he never watched or downloaded pornography on the computers seized from his office.

"He maintains his innocence of these charges and awaits the outcome of the investigation."

Andrew Mitchell, the Tory former international development secretary and friend of Mr Green, claimed that information from the raid had been “leaked nine years later to blacken the name of a serving Cabinet minister and I think that is wrong”.

He added: “I think it is highly questionable whether a retired police officer should misuse this sort of material in this way and I think the police need to explain why there was any record kept of entirely legal activity.”

Mr Lewis is now being investigated by the Metropolitan Police over the alleged release of confidential information.

Scotland Yard said in a statement: "Confidential information gathered during a police inquiry should not be made public.

"The appropriate course of action is to co-operate privately with the Cabinet Office inquiry as the MPS (Metropolitan Police Service) has done.

"As is routine for cases of this nature the circumstances of information being made public will be looked at by the Directorate of Professional Standards."