Lord Geidt has resigned this evening as the Prime Minister’s ethics tsar, a day after telling MPs that he nearly left office over the Partygate scandal.

In a brief statement on the official government website, Geidt said: “With regret, I feel that it is right that I am resigning from my post as Independent Adviser on Ministers’ Interests.” He did not give a reason as to why, but it’s not hard to guess. He’s had enough of Boris Johnson.

His departure comes after he appeared in front of the Public Administration and Constitutional Affairs Committee this week and expressed “frustration” over the PM’s conduct relating to lockdown-busting parties in Westminster during the coronavirus pandemic.

“I am glad that the Prime Minister was able to respond to my report and in doing so addressed aspects of the things about which I was clearly frustrated,” he told the cross-party group of MPs.

“Resignation is one of the rather blunt but few tools available to the adviser. I am glad that my frustrations were addressed in the way that they were.”

Now, he’s resigned.

Geidt, who was appointed in April last year, is the second person to resign from the role under Johnson. In 2020, Sir Alex Allan quit after Johnson refused to accept his findings that Home Secretary Priti Patel bullied Whitehall staff.

Responding to this evening’s news, Labour’s Chris Bryant, chairman of the Committees on Standards and Privileges, called for Johnson to quit and praised Geidt. “He was a decent man working for an indecent prime minister. He thought he could discreetly bring about incremental change but he was repeatedly lied to by Number 10. In honour, Johnson should resign.”

Geidt quitting comes a week before the Wakefield and Tiverton and Honiton by-elections – which the Tories are both projected to lose. They take place next Thursday. This resignation piles on the pressure.