According to a statement posted to the government website on Wednesday, Boris Johnson’s ethics adviser Lord Geidt has tendered his resignation.

His statement read: “With regret, I feel that it is right that I am resigning from my post as Independent Adviser on Ministers’ Interests.”

Speaking to the House of Commons public administration and constitutional affairs committee on Tuesday, Geidt refused to reject claims he may have considered resignation following Boris Johnson’s fine for breaching Covid rules.

“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 said after being pressed by Labour MP John McDonnell, adding: “Resignation is one of the blunt but few tools available to the adviser. I am glad that my frustrations were addressed in the way that they were.”

Deputy prime minister Dominic Raab has claimed this morning that Lord Geidt’s “pretty rough grilling” by the committee earlier this week may have influenced his decision to  resign. 

Raab told Sky News: “Well, the stated reasons, of course he set out overnight, but were very limited. He just said he thought it was the right time to step down. Let me tell you what I know.

He went on: “First of all he had been engaged with the prime minister in No 10 this week and discussing staying on for six months so I think my understanding had been he was committed to the role. I think he had a pretty rough grilling by MPs this week. I think sometimes we in the media as politicians maybe underestimate how civil servants feel with that kind of scrutiny.

“And thirdly, there was a particular issue, a commercially sensitive matter in the national interest, which he was asked to look at. I don’t know which aspect of this, I suspect there will be, in fact I know there will be, an update from No 10 later.”

Raab also confirmed to Times Radio earlier today that Johnson is seeking to replace Geidt, saying he “think[s] that No 10 have made that clear.”

When quizzed over whether he thought the incumbent government always operates in an ethical manner the deputy PM told Sky News: “Yes, I do.

Labour MP Chris Bryant, who chairs the Commons standards and privileges committee, said via Twitter: “Christopher Geidt is one of the most honourable men I have ever met. In the end 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 No 10. In honour Johnson should resign.”

Bella Wallersteiner, a senior parliamentary assistant for a Conservative MP, referred to Geidt’s Tuesday committee appearance in a tweet, writing: “Why did Lord Geidt put himself through the pain of Public Admin Committee on Monday, only to resign today…”

Also responding to the resignation, Liberal Democrat chief whip Wendy Chamberlain MP said: “When both of Boris Johnson’s own ethics advisers have quit, it is obvious that he is the one who needs to go. This prime minister has constantly lied and broken the laws he wrote. It’s clear as day that he has broken the Ministerial Code too.

“For the good of Britain, the next resignation we should be hearing about is that of Boris Johnson,” she went on.

An ex parliamentary commissioner for standards has complained that the exchange of letters between Geidt and Boris Johnson regarding the former’s resignation have not been published. 

Sir Philip Mawer noted that he was “hugely disappointed but not surprised” by Lord Geidt’s decision to quit but that his dissatisfaction in the post was “apparent for a while”, including in his recent annual report.

Sir Philip told BBC Radio 4’s Today programme that if the letter and the prime minister’s reply are not published, then I think people will draw their own conclusions and it won’t be favourable to the prime minister.”