Boris Johnson “did not immediately recall,” that he had been briefed about an investigation that found the former deputy chief whip Chris Pincher behaved inappropriately in 2019, the Cabinet Office minister Michael Ellis has claimed. The former Foreign Office permanent secretary Simon McDonald published an extraordinary letter on Tuesday suggesting No 10 had repeatedly misled the public about what Johnson knew about past claims against Pincher. Journalists were initially told on Friday that the prime minister did not know about “specific” allegations against Pincher – and that his appointment as deputy chief whip, a role that includes pastoral care, could not be held up on the basis of unsubstantiated claims. On Monday, Johnson’s spokesperson said he had known about complaints, but that these had been “resolved”. However, responding to an urgent question from the deputy Labour leader, Angela Rayner, Ellis conceded the prime minister had been informed about an internal investigation that upheld a complaint about Pincher’s behaviour in 2019. Ellis said: “The prime minister was made aware of this issue in late 2019. He was told that the permanent secretary had taken the necessary action. No issue therefore arose about remaining as a minister,” he said. “Last week, when fresh allegations arose, the prime minister did not immediately recall the conversation in late 2019 about this incident. As soon as he was reminded, the press office corrected their public line.” He insisted: “The position is that the prime minister acted with probity at all times.” Speaking shortly before Ellis, Johnson’s official spokesperson denied that he and other No 10 officials had misled reporters on Friday or Monday. “We always seek to provide the information we have at the time,” the spokesperson said. “This information does take time to establish.” He said Johnson was briefed in late 2019 about the complaint about Pincher’s behaviour at the Foreign Office. Asked why ministers and No 10 officials said Johnson did not know about any specific claims, the spokesperson argued the prime minister had simply forgotten about a briefing dating back “a number of years”. “At the time, last week, that was the prime minister’s view,” he said. “You will appreciate that it takes some time to establish that he was briefed, albeit we don’t think in a formal meeting, about this. That’s why we sought to update on Monday.” Asked if he planned to tell journalists the truth at the briefing, the spokesman said he did, saying also that he did not plan to resign. Pincher, the Tamworth MP, resigned as deputy chief whip on Friday evening, admitting that he “drank far too much”, and “embarrassed myself and other people”. He is understood to have been accused of groping some individuals present at an event at the Carlton Club in central London. McDonald’s letter said the behaviour investigated in 2019 had been of a similar nature. Even on Tuesday morning, the deputy prime minister, Dominic Raab, who was foreign secretary when Pincher was investigated, was continuing to insist the prime minister had not been briefed about it. Challenged about McDonald’s letter, he said: “That’s news to me, I wasn’t aware of that. It’s not clear to me that that is factually accurate.” He added: “I have discussed this with the prime minister over the last 24 hours. It is not my understanding that he was directly briefed.” Describing the 2019 investigation, Ellis said: “The exercise established that while the minister meant no harm, what had occurred caused a high level of discomfort. The minister apologised, and those raising the concern accepted the resolution.” Rayner said the government’s explanation “just will not wash”, asking in the light of the 2019 case: “Why did the prime minister allow him to stay in post?” She warned that since the resignation of Johnson’s ethics adviser, Christopher Geidt, there had been an “ethical vacuum” in Downing Street. Ellis said it was important not to prejudge any case, stressing the importance of preserving the anonymity of victims, and warning: “It is possible that a police investigation may follow.”