The former Scotland Yard detective who examined computer equipment from First Minister Damian Green’s office nine years ago has said he was "shocked" by the amount of pornography he found on it.

Neil Lewis, who left the force in 2014 told the BBC there were "thousands" of thumbnail images of legal pornography on the computer used by Theresa May's deputy, who is currently the subject of a Cabinet office investigation over the allegations.

"The computer was in Mr Green's office, on his desk, logged in, his account, his name," Mr Lewis said.

"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."

The pornography that was viewed was not illegal, but the cabinet office investigation will have to investigate whether Mr Green has broken the ministerial code, which states that holders of public office should be "truthful".

A spokesperson for Mr Green 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."

Mr Green also faces allegations he touched a female journalist’s knee over a drink and told her his wife “is very understanding.”

He also denies these allegations.

The raid on Mr Green’s office by counter-terrorism forces in 2008, which ended with his being arrested under the Official Secrets Act while serving as Shadow Immigration Minister, was highly controversial.

Mr Green has spoken about the pornography allegations previously, when they first emerged several years ago. Several weeks ago he said they were “completely untrue” and “political smears.”