Boris Johnson’s attempt to relaunch his premiership suffered a fresh blow on Wednesday night when his ethics adviser, Lord Geidt, dramatically quit after conceding the prime minister may have broken the ministerial code over the Partygate scandal. In a statement released on Wednesday evening, Geidt said: “With regret, I feel that it is right that I am resigning from my post as independent adviser on ministers’ interests.” The resignation, the second from an ethics adviser in less than two years, threatens to overshadow Johnson’s attempts to shrug off the public outcry over Partygate, and the subsequent confidence vote from his own MPs last week. A Government spokesperson said: “We are surprised by this decision, given Lord Geidt’s commitment to the role, to the prime minister, and in his evidence to the House of Commons just yesterday. “This week, the independent adviser was asked to provide advice on a commercially sensitive matter in the national interest, which has previously had cross-party support. No decision had been taken pending that advice. “Whilst we are disappointed, we thank Lord Geidt for his public service. We will appoint a new adviser in due course.” Geidt’s predecessor, Alex Allan, quit in November 2020 after the prime minister ignored his finding that Priti Patel had bullied civil servants. The ethics tsar faced a tough grilling from a cross-party committee of MPs earlier this week, during which he conceded it was “reasonable” to suggest Johnson may have broken the ministerial code – which includes an overarching duty to act in accordance with the law. It is understood the robust evidence session confirmed in Geidt’s mind that his position was no longer tenable. One person who had spoken to him said he was “sick of being lied to”, while another said Geidt was “frustrated” at his portrayal as a “patsy”. After what one friend called a “long night of the soul”, he sent a strongly worded letter to Johnson on Wednesday. Serious breaches of the code are meant to lead to the minister’s resignation. Johnson is already facing an investigation by the House of Commons privileges committee over whether he broke it on another count – by misleading parliament about whether lockdown-busting parties took place. The 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. “For the good of Britain, the next resignation we should be hearing about is that of Boris Johnson.” Labour’s deputy leader, 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?” She added: “The person who should be leaving Number 10 tonight is Boris Johnson himself. Just how long does the country have to wait before Tory MPs finally do the right thing?” Geidt’s resignation came just as Johnson’s team were nursing hopes that they had heard the last of Partygate for a few months, after he survived last week’s vote of no confidence by backbench Tory MPs. His departure will raise fresh questions about how Johnson has conducted himself throughout the Partygate furore. Rebel MPs hoping to force him out failed to win last week’s vote, though 148, or 41%, did not back him. They are now awaiting a fresh trigger to action. If the privileges committee find Johnson has breached the code by lying to parliament, they could push for party rules to be changed to allow another vote. In his annual report, published at the end of last month, Geidt appeared to suggest that he had deliberately not made a recommendation on whether Johnson had broken the ministerial code, because the prime minister – who oversees the system – might ignore him. “If a prime minister’s judgment is that there is nothing to investigate or no case to answer, he would be bound to reject any such advice, thus forcing the resignation of the independent adviser. Such a circular process could only risk placing the ministerial code in a place of ridicule,” he said. At Tuesday’s committee hearing, Geidt underlined the fact that he is not independent from the prime minister, who makes the final decision about whether the ministerial code has been breached. “The point there is I’m an asset of the prime minister as a minister of the crown, rather than a free-orbiting adviser with a different source of authority,” he told the public administration and constitutional affairs committee. “There is some small limitation on the capacity of the independent adviser to be truly independent.” Another watchdog, the committee on standards in public life, recently criticised Johnson for failing to give Geidt sufficient independence to do his job adequately. The committee’s chair, former MI5 chief Jonathan Evans, said it was “highly unsatisfactory” that No 10 had not accepted in full a wide-ranging package of reforms recommended by his committee, and warned: “Suspicion about the way in which the ministerial code is administered will linger.” Johnson will now face the challenge of trying to recruit a third ethics adviser. Labour’s Chris Bryant, the chair of the standards committee, who described Geidt as “thoroughly decent”, said: “We all thought how on earth is Boris going to be able to replace the last one and now who on earth would take the job on? If the Tories think the standards issue is going to go away, I hope this will disabuse them.” Neither Geidt nor the Cabinet Office intend to provide further explanation of his thinking, but he made clear in Tuesday’s hearing that he was not enjoying the limelight. One Whitehall source also suggested he had become increasingly uncomfortable with the government’s approach to the rule of law. His departure comes as the government is preparing for two crucial byelections next week in Wakefield and Tiverton. If the Tories lose both seats, it would be widely read at Westminster as a signal that Johnson has become a drag on their electoral prospects, jeopardising a swath of seats at the next general election. Geidt took over after the resignation of Allan. He took on the job pledging to uphold the standards of the role, but was soon given the tricky job of deciding whether Johnson had broken the ministerial code over the funding of the No 11 flat refurbishment via a Tory donor. Geidt exonerated Johnson, saying he believed the prime minister’s claims that he had not known where the money was coming from. However, he showed the first signs of frustration with his boss after it later became public that Johnson had failed to disclose crucial text messages with the donor, Lord Brownlow. Geidt wrote a letter criticising Johnson for acting “unwisely” but cleared him of being deliberately misleading.