The government’s former chief scientific adviser criticised Boris Johnson’s “impossible flip-flopping” and “bipolar decision-making” in diary entries released to the Covid inquiry.
Sir Patrick Vallance also wrote of “chaos as usual” in Downing Street after a meeting on social-distancing.
The entries were read out at the start of stage two of the inquiry, which will examine the political decision-making.
The government has said it acted to save lives and protect the nation.
Mr Johnson will give evidence in person to the inquiry later this year, along with other ministers, advisers, civil servants and health officials.