The phone call that Boris Johnson was bracing for finally came as he was preparing for Sunday’s Platinum Jubilee finale. Conservative Party grandee Graham Brady confirmed that more than 15% of the prime minister’s own MPs had submitted letters of no-confidence. A vote on his future was imminent.

For hours, though, Johnson was unable to react. Instead he sat looking untroubled in a makeshift royal box near Buckingham Palace watching a parade of soldiers, James Bond cars and celebrity bakers celebrate the Queen’s 70 years on the throne. A couple of seats away sat Labour leader Keir Starmer, unaware of the new threat to his political rival.

The four-day Jubilee extravaganza came after months of meticulous planning. By contrast, the quickfire Conservative leadership vote was the result of months of unease over Johnson’s conduct that boiled into anger at "partygate” — revelations of illegal gatherings in Downing Street during the pandemic.