Damian Green with the prime minister. The Cabinet Office is already investigating claims that he propositioned a former Tory activist

Theresa May’s deputy, Damian Green, was rocked last night by a former police chief’s claim that pornographic material was discovered on one of his parliamentary computers.

A statement prepared by Bob Quick, a former assistant commissioner at the Metropolitan police, claimed the material was discovered by officers during an inquiry into government leaks in which Green was embroiled in 2008.

Quick, who headed the leak investigation, confirmed to The Sunday Times yesterday that his officers had reported finding “extreme” pornographic material on a parliamentary computer from Green’s office.

He will give evidence tomorrow to an inquiry into Green already under way by Sue Gray, Whitehall’s head of propriety and ethics.

Quick, who used to command the Met’s anti-terrorist squad, drew up the statement for the