The situation threatened to destabilise the minority government as Brexit Secretary David Davis warned the Prime Minister he will quit if his colleague is forced out. 

Ex-Detective Constable Neil Lewis discovered pornography on a computer seized from the minister’s office during a Scotland Yard raid when the Tories were in opposition. 

He told the BBC he was “shocked” at the volume of images, none of which were illegal. 

He insisted he had “no doubt whatsoever” it was accessed by Mr Green, now First Secretary of State.  

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

“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.” 

Similar material was found on Mr Green’s laptop, he claimed.  

Mr Green, then shadow Immigration Minister who served under shadow Home Secretary David Davis, was arrested by Scotland Yard in November 2008 in a probe led by Assistant Commissioner Bob Quick. 

His home and offices in Kent and Westminster were searched. 

Mr Quick went public with his pornography claim last month but Mr Green branded him “tainted and untrustworthy”.  

Mr Green has vehemently denied viewing pornography on his Westminster computer.  

Tory MP Andrew Mitchell said Mr Green was entitled to be taken at his word. 

“I think the hounding of Mr Green over information which everyone is clear was entirely legal and which he has emphatically denied either downloading or viewing is completely wrong,” he said. 

The Cabinet Office is set to publish its investigation findings within days.