Boris Johnson’s chief of staff unexpectedly cancelled a regular meeting with advisers on Friday, sparking speculation that Number 10 sackings could be imminent.

Dan Rosenfield, the long-time civil servant who became Mr Johnson’s chief of staff only a year ago, had long been tipped by Whitehall insiders as someone who could be moved on.

There was also a sighting of Antonia Romeo, the permanent secretary at the Ministry of Justice, who was considered for the civil service’s top job last year, entering Downing Street.

Cabinet ministers have said that the Prime Minister is preparing to overhaul the “culture” in Downing Street in the wake of politically damaging allegations of lockdown-breaking parties.

He will address Parliament after the publication of a report due next week from Sue Gray, the civil servant investigating the claims. Downing Street departures are expected.

Others whose futures are now in doubt include Martin Reynolds, the Prime Minister’s principal private secretary, and Jack Doyle, the Number 10 director of communications.

On Fridays, Mr Rosenfield regularly holds a meeting with special advisers – political appointees who serve Cabinet ministers – to recap on the week and give out praise or criticism.

But on Friday, the meeting, which has been held virtually in recent weeks due to Covid rules, was abruptly called off.

An email, which The Telegraph has seen, read: “Given the change to Plan B restrictions as announced by the PM this week and that some of you will have made plans around today’s all SpAd meeting being virtual, we will be moving today’s meeting to next week so that we can meet in person.

“We look forward to gathering again in person at No 10 next week!”