England’s chief nurse was dropped from a daily Downing Street briefing on the coronavirus for refusing to back Dominic Cummings, the Guardian understands. In a trial run for the 1 June briefing, Ruth May was asked about Cummings driving his family from London to Durham while his wife had suspected Covid-19. When she failed to back the prime minister’s chief adviser, she is understood to have been dropped from the press conference taking place later that day – though this has been denied by a government minister. May’s removal was first reported by the Independent, citing senior NHS sources, and has been confirmed separately by the Guardian. The scientific and medical experts who appear at the briefing alongside a politician were initially reluctant to get involved in the row surrounding Cummings, who, while in Durham, also made a 60-mile round-trip to a beauty spot, which he said was to test his eyesight ahead of a longer journey back to London. On 28 May, Boris Johnson tried to prevent the chief medical officer for England, Chris Whitty, and the chief scientific adviser, Sir Patrick Vallance, from answering questions on the subject, before Whitty said that neither he nor Vallance wished to comment on politics. However, on 30 May, England’s deputy chief medical officer, Jonathan Van-Tam, caused embarrassment for the government by saying, in response to a question about the alleged lockdown breach: “In my opinion the rules are clear and they have always been clear,” he said. “In my opinion they are for the benefit of all. In my opinion they apply to all.” A day later, another deputy chief medical officer for England, Jenny Harries, replied “Absolutely” when asked whether she agreed with Van-Tam. She added: “I thought his exposure of what he felt was exactly right,” she said. “We usually say exactly the same things because we think in public health terms, and I think that’s right. From my own perspective, I can assure you that on a matter of personal and professional integrity, I will always try to follow the rules, as I know he does.” The timing of May’s removal suggests that the government was wary of a senior medical adviser to the government implicitly criticising Cummings for a third day in a row as it desperately tried to move the news agenda away from his actions. Van-Tam has not appeared at a press conference since his comments on 30 May. The government’s advisers have generally been on-message at press conferences and supportive of Downing Street, although there have been divergences. Whitty and the UK’s other medical officers vetoed the government’s attempt to lower the coronavirus alert level from four to three. On Wednesday, Johnson said that it was premature to make judgements about what the government could have done better in its response to the coronavirus pandemic. However, Whitty said: “I think there is a long list, actually, of things that we need to look at very seriously. If I was to choose one, it would probably be looking at how we could ... speed up testing very early on in the epidemic. Many of the problems that we have had came because we were unable to actually work out exactly where we were.” An NHS spokesperson suggested the Guardian contact the government, saying: “If someone doesn’t appear, it’s up to Downing Street.” They added that May was “out there saving lives”. On Friday, the transport secretary, Grant Shapps, played down reports, saying: “I don’t think it is true … I am absolutely sure she has been a regular contributor before and I am sure she will be back here again.” Downing Street has been approached for comment.