BREXIT secretary David Davis has threatened to quit the government if Theresa May sacks the Deputy Prime Minister for storing an “extensive” amount of pornography on his work computer.

With just three days to go until May’s “make or break” meeting with Jean Claude van Juncker in Brussels, the Tory leader faces the real prospect of having to choose between losing her Brexit secretary or keeping a man accused of using pornography for hours at a time in his parliamentary office as her number two.

Former Scotland Yard detective Neil Lewis has said that Damian Green’s House of Commons PC history was filled with porn.

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The cop said it was unlikely anyone other than the MP could have been involved.

“It was so extensive, whoever had done it would have to have pushed Green to one side to say ‘Get out, I’m using your computer’,” he said.

The allegations date back to November 2008, when Green, now First Secretary of State, was the immigration spokesman for the Tory opposition.

Police raided his office after he embarrassed the Labour government with leaks from the office of Jacqui Smith, the Home Secretary at the time.

The Home Office, keen to find out who had been sending information to Green, seized his office computer and detained the MP for nine hours.

No charges were brought against Green MP or civil servant Christopher Galley, who had leaked the information to Green.

The officer in charge of the investigation, Bob Quick was criticised by MPs, with a specially constituted Commons committee accusing the former Assistant Commissioner of poor leadership.

Last month, after a journalist said she had been sexually harassed by Green, Quick said that police had found pornographic material on the computer, but had not pursued the matter, or told the MP that it’d been discovered. Yesterday Lewis, annoyed by the way in which Quick had been dismissed, came forward to say he has details of exactly what was on Green’s machine.

He stressed that none of the images were “extreme”.

However, he said over a three-month period they had been viewed extensively, sometimes for hours at a time.

“The computer was in Green’s office, on his desk, logged in, his account, his name,” said Lewis.

“In between browsing pornography, he was sending emails from his account, his personal account, reading documents.

“It was ridiculous to suggest anybody else could have done it.”

An inquiry into Green’s behaviour is expected to land on the Prime Minister’s desk over the weekend, and, it looks like he may be expected to fall on his own sword.

Friends of Green rallied round, attacking the retired constable for keeping details about the investigation and using it in this way.

“Nine years later, after a pretty contentious raid of a senior politician’s office, entirely legal information is leaked to blacken the name of a serving Cabinet minister, and I think that is wrong,” Tory MP Andrew Mitchell said.

Another friend of Green told the Press Association he was “gobsmacked” and found it “deeply concerning that a former police officer who freely admits talking to Bob Quick is putting confidential and non-illegal details of a police investigation into the public domain, and equally outraged that the BBC would use such information from an unreliable source”.

According to reports, a “mutual friend of Davis and Green” has said the Brexit Secretary made it clear to the Prime Minister, “in words of one syllable” that he would find it difficult to stay in his job if Green is forced out of government.

Speaking to reporters at his Kent home, Green maintained his innocence: “I did not download or look at pornography on my computer.”