No 10 is facing questions about why it did not disclose that Sir Mark Sedwill, the UK’s most senior civil servant, had coronavirus at about the same time as Boris Johnson, Chris Whitty and Matt Hancock were struck down with the illness. The revelation – many weeks after Sedwill was diagnosed – means that almost all the senior people in charge of the UK’s coronavirus response had the illness in late March or early April. It raises particular questions about why Johnson allowed a crucial cabinet meeting to go ahead on Tuesday 24 March, one day after the lockdown was imposed, which was attended in person by Whitty, the chief medical officer, Hancock, the health secretary, and Sedwill, the cabinet secretary. Johnson, Hancock and Whitty confirmed they tested positive for the virus two days later. Dominic Cummings, Johnson’s chief adviser, was also later confirmed to have had coronavirus at about the same time. Sedwill was working at home throughout his illness but No 10 did not reveal at the time that he had tested positive. When asked almost daily at briefings about the state of Sedwill’s health, Downing Street said he was “fine” or working as normal. Sedwill, who is also national security adviser, is the most powerful civil servant in Britain. Asked whether the public had been misled, Johnson’s official spokesman said that he personally only became aware recently that Sedwill had been ill and that the cabinet secretary had continued to work over that period. The spokesman did not have the exact dates that Sedwill had coronavirus but Civil Service World reported that he tested positive in April and was ill at about the same time as Johnson. Asked why Sedwill’s illness and the date he tested positive had been kept from the public, a Cabinet Office spokesman said: “After experiencing mild symptoms the cabinet secretary tested positive for coronavirus in April. In line with the government’s guidance, the cabinet secretary self-isolated. He continued to lead the civil service’s implementation of the government’s response to coronavirus throughout this period.” Downing Street has already been criticised for allowing daily press conferences to continue without physical distancing in place while the crisis was underway. In the last week of March, when the lockdown was imposed, Johnson, Hancock, Sedwill and Whitty all chose to attend in person. Another senior figure to have had the virus at about that time was former scientific adviser Prof Neil Ferguson, whose modelling team at Imperial College influenced the decision to impose a lockdown.