Boris Johnson placed his ethics adviser in an “impossible and odious” position by asking him to “risk a deliberate and purposeful breach of the ministerial code”, letters from the adviser show. Johnson revealed in his reply that he had asked Christopher Geidt to consider plans by the government to continue some steel tariffs – a move that could break World Trade Organization terms – but hinted he was unsatisfied with the explanation. Lord Geidt’s resignation letter said he was “tasked to offer a view about the government’s intention to consider measures which risk a deliberate and purposeful breach of the ministerial code. This request has placed me in an impossible and odious position”. He said he had initially asked the prime minister to justify his position openly but came to the conclusion his role was untenable. “The idea that a prime minister might to any degree be in the business of deliberately breaching his own code is an affront. A deliberate breach, or even an intention to do so, would be to suspend the provisions of the code to suit a political end. “This would make a mockery not only of respect for the code but licence the suspension of its provisions in governing the conduct of Her Majesty’s ministers. I can have no part in this.” Geidt quit his role on Wednesday night after a difficult evidence session with MPs on Tuesday, where he said it was “reasonable” to suggest Johnson may have broken the ministerial code, which includes an overarching duty to act in accordance with the law. The prime minister’s official spokesperson said Geidt would not necessarily be directly replaced. He said Johnson believed it important that the ministerial code was upheld, but that no final decision had been made “on how best to carry out that function, whether it relates to a specific individual or not, particularly given some of the issues that have been raised recently [that] the prime minister alludes to in his letter. So he will carefully consider that before setting out next steps.” Johnson wrote in his reply to his former adviser that it was his intention to seek Geidt’s “advice on the national interest in protecting a crucial industry, which is protected in other European countries and would suffer material harm if we do not continue to apply such tariffs. “This has in the past had cross-party support. It would be in line with our domestic law but might be seen to conflict with our obligations under the WTO. In seeking your advice before any decision was taken, I was looking to ensure that we acted properly with due regard to the ministerial code.” The row centres on tariffs placed on cheap imported steel, after officials from the Trade Remedies Authority advised that the tariffs should be dropped on certain types. Liz Truss has signalled she will overrule that advice and legislate to continue tariffs on some types, in order to protect domestic industry. Speaking in the House of Commons when answering an urgent question from Labour, the Cabinet Office minister, Michael Ellis, suggested the government believed Geidt had come to the end of his tether and blamed opposition politicians. He said it was important that “whoever holds this role is not under constant pressure, political pressure, to attack the prime minister for policy and political reasons. And if they don’t then they are accused of being a lackey or a patsy. “That’s not something that our independent advisers on ministerial interests deserve … It’s in the public interest that party politics is not allowed to put pressure where it doesn’t belong.” Geidt’s immediate predecessor, Alex Allan, quit in November 2020 after the prime minister ignored his finding that Priti Patel had bullied civil servants. Geidt faced a tough grilling from a cross-party committee of MPs earlier this week, and sources said they believed 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 the strongly worded letter to Johnson on Wednesday. Johnson is already facing an investigation by the House of Commons privileges committee over whether he broke the code on another count: by misleading parliament about whether lockdown-busting parties took place. Labour’s Fleur Anderson, who called the urgent question, said: “The prime minister has now driven both of his own handpicked ethics advisers to resign in despair. Two in two years. It’s a badge of shame for this government.”