The Prime Minister’s official spokesman said he was “not aware” of Mr Johnson doing any work on a biography of William Shakespeare while in office.
Mr Johnson did not chair the first five meetings of the Cobra emergency committee in January and February 2020, but Downing Street insisted this was not unusual and was nothing to do with any book.
No 10 faced questions after a Sunday Times report suggested officials fear Dominic Cummings will use an appearance before MPs to accuse Mr Johnson of missing key meetings on the crisis because he was working on a biography of Shakespeare, because he needed the money to fund his divorce from Marina Wheeler, his second wife.
Asked if the Prime Minister had spent time on the book, his official spokesman said: “No, not that I’m aware of.”
The Prime Minister has been “ensuring the public are kept as protected as possible during this global pandemic”, the spokesman added.
In response to the suggestion the book was responsible for him missing Cobra meetings, the spokesman said: “No, and I think there are a number of incidents I can run you through where Cobras have been chaired by relevant secretaries of state.”
Mr Cummings, who was the Prime Minister’s senior aide in No 10 until last year, will give evidence to MPs examining the coronavirus response, on Wednesday.
Ahead of his appearance, he has set out his criticisms of the Government’s approach in a series of messages on Twitter, claiming the original response to the coronavirus outbreak was to pursue a strategy of “herd immunity”.
In a series of explosive tweets, he said the policy – to build up resistance in the population by allowing some spread of the disease – was only dropped in March last year after a warning it would lead to a “catastrophe”.
The Prime Minister’s official spokesman told reporters: “Herd immunity from infection has never been government policy.”
The spokesman added: “At all times we have been guided by the data and the latest evidence we have had through this coronavirus pandemic.
“We set out our initial plan, which was published on March 3 and presented at press conferences.
“As our understanding of the virus progressed, more data became available, it was clear that a national lockdown was needed to suppress the curve, save lives and protect the NHS from being overwhelmed.”
Asked if Mr Johnson believed Mr Cummings was a liar, the spokesman said: “I haven’t asked him that question.”