Behavioural scientists advising the government have warned that the breaking of social distancing rules by Matt Hancock could make others less likely to adhere to Covid restrictions. The health secretary has admitted he breached social distancing guidelines after he was pictured in the Sun in a “clinch” with Gina Coladangelo, a university friend who he had appointed non-executive director at the Department of Health and Social Care (DHSC). The photographs allegedly date from 6 May, and indoor contact with someone you do not live with was not allowed until 17 May. Last year Hancock said he would back the police in any action they wished to take over Prof Neil Ferguson breaking social distancing rules by having his lover visit him at his home, adding that Ferguson was correct to step down from his position on the government’s Scientific Advisory Group for Emergencies (Sage). Hancock told Sky News that the social distancing rules “are there for everyone” and are “deadly serious”. The prime minister’s spokesperson said on Friday he had accepted Hancock’s apology for his own rule-breaking and “considers the matter closed”. But experts warned that the health secretary’s actions could undermine public adherence to ongoing restrictions, pointing to the impact of breaches by Boris Johnson’s former aide Dominic Cummings during the first lockdown, when he travelled to his family’s Durham farm and subsequently took a family trip to Barnard Castle. “‘Do what I do’ can have a bigger impact that ‘Do what I say’, particularly when combined with public anger,” said John Drury, professor of social psychology at the University of Sussex and a member of the Sage subcommittee advising on behavioural science, Spi-B. “We know from research on the Cummings incident that rule-breaking at the top undermines social cohesion and adherence.” Dr Elise Paul, an investigator on the Covid-19 Social Study at University College London, said there were several similarities between the Cummings and Hancock situations. “Although Hancock has apologised for his transgression, the impact on public confidence may be just as bad or worse than that of the Cummings situation, given his particular role in government and that the other person involved appears to be someone whom he supervises,” she said. Drury said it was positive that Hancock has apologised, but that may not be enough. “If the public are being fined for the same kinds of actions, will the health secretary also be fined, to communicate that he doesn’t have some kind of special dispensation?” he said. Prof Susan Michie, director of UCL’s centre for behaviour change and also a member of Spi-B, said: “There is good evidence that perceived fairness and a sense of being part of a collective effort are important for supporting people to adhere to guidance such as restrictions which may be hard or aversive to stick to.” As an example of perceived unfairness, Michie cited allowing large crowds at sporting events while banning parents from children’s sports days. “An elected government minister found to break distancing rules without appropriate consequence may become another example,” she said. But Stephen Reicher, professor of psychology at the University of St Andrews, who is also on Spi-B, said Hancock should be judged on his performance as health secretary. “And on that, I agree with Boris Johnson as summarised in his WhatsApp exchanges with Dominic Cummings,” he said. According to messages released by Cummings, allegedly dating to March last year, the prime minister called his health minister “totally fucking hopeless”. “But I also believe in due process,” said Reicher, “which is why we need – and urgently need – a full public inquiry rather than snippets of tittle-tattle so we can have a proper evaluation of the performance of Hancock and his colleagues from which informed decisions about their future can be made.”