He departs from the role of director of communications little more than five months later "to allow a new No 10 team to be built".

In the process, he becomes the latest high-profile figure to leave Downing Street and the second in less than 24 hours after Morgan McSweeney resigned as Sir Keir's chief of staff.

Allan arrived as part of a shake-up to the Downing Street operation as the prime minister tried to improve communications across his administration.

The 55-year-old had previously worked as a communications adviser for Sir Tony, both in opposition and in government, until 1998 when he decided to pursue a business career.

Allan's LinkedIn profile details how he worked for BSkyB before he founded the Portland Communications agency, which specialises in reputation management for businesses, public bodies and high profile individuals.

He was also involved in charitable and investment activities before his return to government.

Allan was the fourth person to hold the role of director of communications under Sir Keir.

Matthew Doyle resigned as Sir Keir's communications chief nine months after Labour won the 2024 general election, emailing colleagues that it was "time to pass the baton on".

He was replaced by Steph Driver and James Lyons, both of whom have since left No 10.

On Sunday, McSweeney resigned as Sir Keir's chief of staff over calls for someone to be held accountable for the decision to appoint Peter Mandelson as UK ambassador to the United States.

McSweeney had succeeded Sue Gray, who left the role in October 2024 just months after Labour won the general election.

Baroness Gray, who investigated Covid-era rule-breaking in Boris Johnson's government when working as a senior civil servant, left Sir Keir's team following reports of a power struggle between her and other aides.

Paul Ovenden also resigned as No 10's director of political strategy in September 2025 after offensive messages he had sent in 2017 surfaced.

Cabinet ministers have expressed support for the prime minister, as he prepares to face Labour MPs.

Sir Keir Starmer's administration appears rudderless after the loss of two key aides, writes Chris Mason.

Starmer's chief of staff departs at a time the PM is isolated and in potential peril.

McSweeney, long considered instrumental to the rise of the PM, derived his power and influence from his track record as a political strategist.

The former Labour MP says evidence was disregarded in the decision to make Mandelson ambassador to the US.