Boris Johnson sat through Platinum Jubilee parade knowing he faced leadership vote the next day

Prime minister was in front of cameras for several hours, just yards away from royals and Keir Starmer

Boris Johnson was told that he faced a vote to remove him as Conservative leader before he attended the Queen’s Platinum Jubilee celebrations on Sunday.

It meant that the prime minister had to spend hours in front of TV cameras watching the “People’s Pageant” parade from the VIP seats in front of Buckingham Palace.

Mr Johnson seemed in cheerful mood for much of the event, smiling as he sat alongside wife Carrie behind Prince William, the Duchess of Cambridge and their children George, Charlotte and Louis.

But at one point he was caught by photographers clutching his forehead with a serious expression on his face as he apparently looked at a message on a mobile phone.

Just a few feet away were Labour leader Sir Keir Starmer and London mayor Sadiq Khan.

It is understood that the chair of the backbench 1922 Committee Sir Graham Brady informed Mr Johnson by telephone early on Sunday that the number of letters demanding a confidence vote had passed the trigger threshold of 54.

The pair had a lengthy discussion about what should happen next, with Brady suggesting a vote the following day and the PM agreeing.

The timetable followed the format for Theresa May’s confidence vote in 2018, with Sir Graham to make an announcement at 8am on Monday and Tory MPs voting in a Commons committee room between 6pm and 8pm with the result to be declared at 9pm.

After leaving the pageant, Mr Johnson is understood to have drawn up a plan of action with his closest allies in his flat above 11 Downing Street.

The prime minister was seen clutching his forehead during the Jubilee parade (POOL/AFP via Getty Images)

Those present included chief of staff Steve Barclay, Tory chief whip Chris Heaton-Harris, Cabinet Office minister Nigel Adams, communications director Guto Harri, Conservative Party official Ross Kempsell and unofficial adviser Sir Lynton Crosby, the architect of Mr Johnson’s successful election campaigns.

Over around three hours, a plan was worked out for Mr Johnson to write a letter to each Tory MP and for a rebuttal note making the case for his continued premiership also to be sent out to counter the one-page briefing distributed by rebels over the weekend.

Mr Johnson’s letter was completed and approved by the end of the evening for dispatch this morning.

Mr Johnson hosted Estonian PM Kaja Kallas in 10 Downing Street hours before the vote (Getty Images)

The PM this morning spoke by phone with Ukrainian president Volodymyr Zelensky and hosted Estonian prime minister Kaja Kallas at No 10, as Downing Street briefed that he was not allowing the threat to his position to distract him from the challenges facing the UK and the world.

Later he left No 10 for the Palace of Westminster to speak personally to individual MPs who his allies believed could be persuaded to stick with him, before addressing the parliamentary party at a meeting of the 1922 Committee in the hours before the vote.