Elsewhere in the podcast, Mr Harri described his concerns in Downing Street after Mr Johnson gave a speech to business executives in November 2021 in which he lost his seat, before speaking at length about his visit to Peppa Pig World theme park.
“I think the day job is to keep up appearances. You have to perform so often – at private receptions, behind closed doors at meetings, with visiting dignitaries. And of course you have to give speeches.
“And there was one speech in particular where Boris lost the thread and started talking about the Peppa Pig world, which left a lot of people seriously concerned about his state of mind.”
Mr Johnson had to be taken to hospital in a wheelchair during his coronavirus bout in April 2020, weeks after the initial lockdown was imposed, according to his former spin doctor.
He was unable to walk upstairs to the Downing Street flat and privately feared that doctors would have to perform a tracheostomy.
Johnson “extremely frustrated” by Javid
As the lockdown eased following the vaccine rollout, Mr Johnson is said to have become “hugely frustrated” with Sajid Javid, his then health minister, for not immediately setting out a clear enough reform agenda.
“There was a huge row about ending free universal Covid testing,” Mr Harri continued.
“The Saj dug in with a curiously well-rehearsed line about being asked to disarm while the enemy is still lurking there. But testing cost £2 billion a month.”
He added that Mr Johnson believed the public had become “epileptically bored” by Covid and personally found it “a matter of astonishing irrelevance” as long as preparations were made for dealing with future pandemics.
“He contributed the day to that occasion and saved a fortune,” Mr Harri said.
On Wednesday, Mr Johnson said he had handed over all his unredacted WhatsApp messages and notebooks from the time of the pandemic to the government in a challenge to Mr Sunak.
He said he wanted the material to be provided in full to the Covid investigation, despite the cabinet so far refusing to submit unredacted messages and documents.
An ally of Sajid Javid said: “This is an interesting version of history. Despite political unwillingness on some sides, Sajid was the champion of NHS reform. The facts about pandemic policies will emerge in the independent investigation.”
A spokesperson for Mr Johnson said: “Boris had no part in this podcast and does not recognize any of its content.”