The UK’s top civil servant is set to give evidence to the Covid-19 inquiry about his scathing views of Boris Johnson’s pandemic-era government.

Simon Case’s appearance has been scheduled for May 23 following his return to work as Cabinet Secretary after he stepped back in October due to a medical matter.

Mr Case is expected to face questions on highly critical WhatsApp messages that emerged during evidence last year, showing his exasperation with the handling of the pandemic under Mr Johnson’s premiership.

In July 2020, before he became Cabinet Secretary, he said: “I’ve never seen a bunch of people less well-equipped to run a country” in a message to Lord Sedwill, who was the civil service chief at the time.

He also described Mr Johnson and his inner circle as “basically feral” and suggested the then-prime minister’s wife Carrie was “the real person in charge” in No 10.

Mr Case was absent from hearings last year when other senior Westminster figures gave evidence, and the rescheduling of his appearance in the months before a general election could cause a headache for Downing Street.

In June 2020, Mr Case accused Rishi Sunak of “totally outrageous” behaviour while he was chancellor, complaining that the now-Prime Minister apparently criticised the lack of enforcement of Covid rules but had been instrumental in blocking powers to do so.

UK Covid-19 Inquiry chairwoman Baroness Hallett excused Mr Case from giving evidence due to ill health during the hearings on the Government’s decision-making late in 2023.

But in a ruling in November she said “it very much remains my intention that Mr Case should give oral evidence to the inquiry”.

She ordered that Mr Case’s lawyers should provide the inquiry with an updated report on his ability to give oral evidence at the end of January 2024 or upon his return to work, whichever was sooner.

The Covid inquiry confirmed on Tuesday that “the module 2 oral evidence of Cabinet Secretary Simon Case has been rescheduled to be heard on Thursday May 23.”