The senior civil servant who led the investigation into lockdown parties in Downing Street is set to be appointed Sir Keir Starmer's chief of staff.
Sue Gray, who authored the report into the partygate scandal, has served for decades in Whitehall and built up a formidable reputation in Government.
The former Cabinet Office ethics tsar resigned on Thursday afternoon, No10 confirmed.
The Prime Minister’s spokesman said: “I can confirm that Sue Gray has resigned from the post of Second Permanent Secretary. This was accepted by the department's Permanent Secretary and the Cabinet Secretary with immediate effect.
“We will not be commenting further on individual personal matters.”
Her appointment follows the dismissal of Sam White, who was Sir Keir’s chief of staff for a year but was unpopular with some in the party and the shadow cabinet.
A Labour Party spokesman said: “The Labour Party has offered Sue Gray the role of chief of staff to the Leader of the Opposition.
“We understand she hopes to accept the role subject to the normal procedures. Keir Starmer is delighted she is hoping to join our preparations for government and our mission to build a better Britain.”
It is understood that Rishi Sunak could theoretically block her from taking up the post in the coming months.
Under rules governing senior civil servant appointments, an application to the Advisory Committee on Business Appointments (ACOBA) is required for a two-year period after leaving office becuase of the sensitive information they have access to as part of their job.
The rules state: "All Permanent Secretaries, including Second Permanent Secretaries, will be subject to a minimum waiting period of three months between leaving paid Civil Service employment and taking up an outside appointment or employment.
"The Advisory Committee may advise that this minimum waiting period should be waived if, in its judgement, no questions of propriety or public concern arise from the appointment or employment being taken up earlier.”
Ms Gray’s son Liam Conlon is the chair of Labour's Irish Society , which is a group formerly led by Sir Keir’s director of communications Matthew Doyle.
Labour sources said Sir Keir is in need of an accomplished cheif of staff to counter the relatively inexperienced, young team he currently has around him.
