Mr Burns stressed he was not trying to make light of the difficulties that millions of people experienced during the pandemic.
He said: “One of my aunts died during the pandemic, not of Covid, and her family had to watch her die through a sort of Perspex screen.
“I don’t for one second diminish the hurt the people feel, how difficult those rules were and precious time that people will never get back. And the Prime Minister understands that.”
Mr Burns urged Tory MPs considering putting in letters of no confidence in Mr Johnson to ask themselves: “What are we doing?
“Not only is he going to survive, he is going to thrive. There was a headline the day after Margaret Thatcher resigned in the Daily Express, a picture of her standing outside No 10 with a huge bouquet of flowers. And it was the day after her amazing, no confidence speech and the headline was simply: ‘What have they done?’
“I think there was a sense in the parliamentary party over the last 10 days of: ‘What are we doing?’ And I think colleagues have pulled back. So I think he will get through this.
“I think he will rededicate himself to delivering for the British people. And I am absolutely confident that not only will he lead us into the next general election, he will win the next general election handsomely for the Conservative Party and for the United Kingdom.”
No 10 declined to comment on whether there was cake at Mr Johnson’s birthday party.
Listen to Conor Burns and Sir John Redwood on Boris Johnson’s crisis-hit 10 Downing Street, as well as The Telegraph’s Nataliya Vasilyeva and Lucy Fisher, on Chopper’s Politics podcast using the audio player at the top of this article, or on Apple Podcasts, Spotify or your preferred podcast app.
