BBC chairman Richard Sharp resigned earlier today after it was found he broke the rules by failing to reveal he helped Boris Johnson secure an £800,000 loan guarantee.

A review by barrister Adam Heppinstall found that the former Tory donor twice breached the code governing public appointments by appearing biased towards the then prime minister.

It found that Mr Sharp risked a perception that he was recommended for the role because he assisted Mr Johnson “in a private financial matter” ahead of his appointment in 2021.

Mr Heppinstall also said there was the risk it would be perceived that he influenced Mr Johnson to recommend him by notifying the former PM of his application before submitting it.

The review came after it emerged that he introduced his friend Sam Blyth, a distant cousin of Mr Johnson who wanted to help him with his financial troubles, to Cabinet Secretary Simon Case ahead of being recommended for the role by the government.

Mr Sharp said he would stand down from overseeing the public broadcaster’s independence at the end of June but insisted that his breach was “inadvertent and not material.”

Following the resignation, Prime Minister Rishi Sunak defended himself against suggestions he should have sacked Mr Sharp weeks ago — arguing that it was right to follow the “proper process.”

The National Union of Journalists welcomed the decision.

General secretary Michelle Stanistreet said: “Richard Sharp has shamefully clung to his position as chair for months, while all around him could clearly see his time was up, so of course it is a relief and proper that he has now finally resigned.

“He had lost the dressing room, he had lost the respect of senior figures in the broadcasting industry and besmirched the reputation of the BBC.

“Now the BBC must move on with a new chair who can help steer the corporation through difficult times and champion public service broadcasting.”

Labour’s shadow culture secretary Lucy Powell said Mr Sharp had “caused untold damage to the reputation of the BBC and seriously undermined its independence as a result of the Conservatives’ sleaze and cronyism.”

“The Prime Minister should have sacked him weeks ago,” she said.

“Instead, it took this investigation, called by Labour, to make him resign.”