“This event should not have happened at the time that it did. I am deeply sorry,and take full responsibility.”

Boris Johnson did not attend the parties and left for his country residence Chequers the night before.

But the damaging relevations about the further parties held at a time of mourning will only add to the pressure on him amidmore calls from MPs for him to vacate the leadership.

MPs are furious with the prime minister who originally denied there were parties held at Downing Street during lockdowns only to confirm this week that he attended one in his official garden but thought it was a “work event.”

A fifth MP,Brexiteer Andrew Bridgen,has called on Johnson to resign,with Chancellor of the Exchequer Rishi Sunak and Foreign Secretary Liz Truss considered the two big rivals positioning themselves for a takeover of the top job.

Opposition Leader Keir Starmer said the prime minister had “degraded” the office.

“An apology isn’t the only thing the Prime Minister should be offering the palace today,” he said.

“Boris Johnson should resign.”

Johnson is awaiting the result of an internal inquiry by civil servant Sue Gray who is investigating the parties and whether they breached lockdown rules.