Lord Geidt handed his resignation letter to the Prime Minister today.
According to a brief statement on the Government’s website, he said: “With regret, I feel that it is right that I am resigning from my post as independent adviser on ministers’ interests."
Just a day earlier, he declined to deny to MPs that he had considered resigning over Mr Johnson’s response to being fined for breaching lockdown rules.
Lord Geidt told the Public Administration and Constitutional Affairs Committee that he had felt “frustration” amid the Partygate scandal.
Lord Geidt
Dominic Lipinski
Prime Minister Boris Johnson
Aaron Chown
He said: “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.
“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.”
It was reported that Lord Geidt had threatened to quit last month after the publication of the Sue Gray report into lockdown breaches in Whitehall unless Mr Johnson issued a public explanation for his conduct.
Lord Geidt is the second person to resign as Mr Johnson’s ethics adviser during his less than three years as Prime Minister.
Sir Alex Allan quit in 2020 after Mr Johnson refused to accept his finding that Home Secretary Priti Patel had bullied civil servants.
Labour reiterated calls for the Prime Minister to step down after news of Lord Geidt's resignation broke.
Angela Rayner said: “The Prime Minister has now driven both of his own hand-picked ethics advisers to resign in despair. If even they can’t defend his conduct in office, how can anyone believe he is fit to govern?
“Yet he remains propped up in office by a Conservative Party that is mired in sleaze and totally unable to tackle the cost-of-living crisis facing the British people.
“The person who should be leaving No 10 tonight is Boris Johnson himself.
“Just how long does the country have to wait before Tory MPs finally do the right thing?”