The two experts who have guided the government’s response to the coronavirus were not asked to approve the controversial new “stay alert” message, the Guardian has learned. Neither Prof Chris Whitty, the chief medical officer for England, nor Sir Patrick Vallance, the government’s chief scientific adviser, were asked to sign off on dropping the “stay at home” advice before Boris Johnson unveiled the new strategy on Sunday night. Their lack of a role amid criticism of the switch in the key message has prompted renewed doubt about the government’s persistent claim it is “following the science” in its response to the virus. It comes as experts who attend meetings of the scientific advisory group on emergencies (Sage) broke cover to criticise the government over its handling of the change in messaging, with some complaining that Downing Street had sidelined them from the process. Speaking in a professional capacity, Prof John Drury, a social psychologist at the University of Sussex and a member of the scientific pandemic influenza group on behaviours (SPI-B), which feeds into Sage on issues including the best ways to communicate government strategy with the public, said the group had “considerable expertise” on health behaviour and emergency communications which had hardly been called on by the government. “Who is advising on the current messaging? Unfortunately it’s not us,” he said. He said that the “stay alert” messaging is “too vague” and that “more precision is needed”. And Prof Susan Michie, of University College London, tweeted: “Lack of clarity can cost lives. Scottish government a good example of clear & consistent messaging. No spin, no self-congratulation, no defence, just honest communication, including of the uncertainties. Engenders trust & adherence; avoids confusion & anxiety.” SPI-B is attended by a range of messaging experts, including specialists in behavioural change from the University of Cambridge, the London School of Hygiene and Tropical Medicine, and King’s College London. When asked if it was correct that Vallance and Whitty had not had sign-off in the House of Commons Boris Johnson said “that’s not right” but did not elaborate on their roles. But at the Downing Street press conference later on Monday, Whitty appeared to contradict the prime minister’s answer in parliament, saying: “Neither Sir Patrick nor I consider ourselves to be comms experts, so we’re not going to get involved in actual details of comms strategies, but we are involved in the overall strategic things and we have been at every stage.” A government spokesperson said: “Sage advice fed into the new strategy as it has throughout the Covid-19 response.” Whitehall sources said neither man had been asked to formally approve the move out of lockdown because such a role fell outside their briefs. “It is not the CMO or CSA’s role to approve government strategy or branding,” one official said. It is understood that, unusually, the Department of Health and Social Care - which Whitty advises - was not involved in drawing up the new strategy and slogan, despite their major implications for public health, and that it was instead developed jointly by No 10 and the Cabinet Office. The Liberal Democrats said that Whitty and Vallance’s lack of sign-off “beggars belief”, given their high-profile role in advising ministers and appearing regularly at the daily press conference. As well as being the CMO for England, Whitty is also the government’s chief medical adviser and head of the public health profession. Vallance, a professor of medicine and expert in drug development, is the head of the government science and engineering (GSE) profession. Sources maintained Downing Street had taken expert advice before the prime minister’s televised address on Sunday night. “The government has developed this roadmap and strategy for coming out of lockdown using scientific and medical advice. The new campaign messaging is based on the guidance developed as part of that roadmap,” the official added. Munira Wilson, the Liberal Democrats’ health spokesperson, said: “The government’s failure to secure the approval of the chief medical officer or the chief scientific adviser for this significant shift in public health messaging beggars belief. If the government is following the science as it has repeatedly claimed to be, working closely with the CMO and CSA on all public messaging should be a given.” The Twickenham MP added: “The new ‘stay alert’ message is deeply confusing, out of step with other UK nations and it’s unclear what scientific guidance – if any – informed this decision. Ministers must explain the basis for the new messaging and who exactly was consulted about the change.” Paul Hunter, a professor of medicine at the University of East Anglia, said the experts’ non-involvement was of concern. “Maybe if they had asked for the involvement of the CMO and CSA they might actually have got a message that people could understand. ‘Stay alert’ is a pretty meaningless phrase that doesn’t mean much to most people or to professors of medicine. “If they weren’t involved in this key decision then how can you continue to claim that you are following the science? To make such a point that you are following the science and then not involve your two most senior scientists in a key decision like this would strike me as being worrying. It’s substantial mixed messaging.”