The former prime minister is due to give evidence next week - and according to The Times, he will issue an "unreserved apology" and admit his government was "initially far too complacent" about the threats posed by the virus.

He is also set to back Matt Hancock who has been severely criticised by senior civil servants, saying the former health secretary was doing "a good job in very difficult circumstances", the paper reports.

The inquiry heard last month that former head of the civil service Mark Sedwill wanted Mr Hancock removed because of questions over his honesty.

Deputy cabinet secretary Helen MacNamara told the inquiry he had "nuclear levels" of confidence and "regularly" told colleagues in Downing Street things "they later discovered weren't true".

Mr Johnson is expected to express regret for boasting about shaking hands with patients on a coronavirus ward and defend the timings of the UK's three lockdowns.

He is set to argue that failing to act would have caused thousands more "miserable and unnecessary deaths - some of them in hospital car parks and corridors".

Last month, England's chief medical officer Professor Chris Whitty told the inquiry that he believes the first lockdown in March 2020 came "a bit too late".

But The Times is reporting that Mr Johnson will claim Prof Whitty was "instrumental in arguing for a delay" - and the possibility of a lockdown was first discussed three weeks before it was enforced.

The ex-PM is also expected to deny saying that he had a "let it rip" attitude towards COVID, with a view to achieving herd immunity.

A source close to Mr Johnson told the Daily Telegraph that the ex-PM will argue that the UK was in a unique position because of its high obesity rates.

"As a nation, we are fatter, less fit, there's lots of factors in our public health that are just facts which made the UK very different from other comparable democracies," the source said.

Mr Johnson is expected to face difficult questions on multiple issues - including partygate, his communications with government colleagues, and the evidence heard so far.

He will say that Downing Street parties had no "material impact" on how well people stuck to lockdown rules.

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The report suggests that the former politician is preparing to argue that his WhatsApp messages have been taken out of context, meaning "dark humour is lost or morphs into mockery".

Eat Out to Help Out is also likely to be discussed, amid claims that the government's COVID-19 taskforce was "blindsided" when the controversial scheme was announced.

Mr Johnson is expected to argue that the policy was "properly discussed" with Prof Whitty and former chief scientific adviser Sir Patrick Vallance.

According to the newspaper, then chancellor Rishi Sunak and de facto chief of staff Dominic Cummings are both set to be largely absent from Mr Johnson's written testimony, which is likely to be published after his appearance in front of the inquiry.

A spokesperson for Mr Johnson said: "Boris Johnson will be at the COVID inquiry next week and is looking forward to assisting the inquiry with its important work."