Pressure is mounting in Downing Street as Keir Starmer faces yet another setback, losing his third key aide in just one week.

Cabinet Secretary Sir Chris Wormald, the most senior civil servant in Britain, has stepped down from No10.

His departure follows a series of high-profile resignations around Downing Street, beginning with Chief of Staff Morgan McSweeney on Sunday.

In a statement, the Cabinet Office said the Prime Minister and Sir Chris had agreed by mutual consent that he would stand down as Cabinet Secretary and head of the civil service with immediate effect.

Sir Chris said: “It has been an honour and a privilege to serve as a civil servant for the past 35 years, and a particular distinction to lead the service as cabinet secretary.

“I want to place on record my sincere thanks to the extraordinary civil servants, public servants, ministers, and advisers I have worked with.

“Our country is fortunate to have such dedicated individuals devoted to public service, and I wish them every success for the future.”

Sir Keir Starmer paid tribute to his departing aide, saying: “I am very grateful to Sir Chris for his long and distinguished career of public service, spanning more than 35 years, and for the support that he has given me over the past year.

“I have agreed with him that he will step down as cabinet secretary today. I wish him the very best for the future.”