Sue Gray has been appointed by Sir Keir Starmer to serve as his chief of staff.
The senior civil servant became a household name during the partygate scandal, authoring the report which found “a failure of leadership and judgement” in Number 10 during Boris Johnson’s premiership.
She has left her role in the civil service ahead of taking up her new role.
It is not clear when Ms Gray will take on the role, as the appointment will need to be checked by the watchdog which oversees new jobs for former ministers and senior civil servants – the Advisory Committee on Business Appointments (ACOBA).
According to the ACOBA website, the body provides advice to the prime minister about appointments.
It will be up to Rishi Sunak to make a final decision on agreeing to the appointment.
Some aspects of the Conservative Party are unhappy that someone they believe contributed to Boris Johnson’s downfall has been tapped for a job by the opposition party.
Johnson loyalist Nadie Dorries said the appointment was “not surprising” – claiming the partygate report was a “stitch up” of Boris Johnson and civil servants.
Red wall MP Mark Jenkinson reacted by saying “all part of the plan” with an emoji of a pair of eyes – again suggesting bias in Ms Gray’s report.
Ms Gray has long had a fearsome reputation in Whitehall, serving as the key enforcer of ministerial behaviour while head of propriety and ethics in the Cabinet Office between 2012 and 2018.
The possibility she could be appointed to the Labour leader’s office was first reported by Sky News on Wednesday.
Ms Gray is the daughter of Irish immigrants and her son Liam Conlon is the chair of Labour’s Irish Society – a group formerly led by Starmer’s director of communications, Matthew Doyle.
Ms Gray’s appointment follows the dismissal of Sam White, who served as Sir Keir’s chief of staff for a year but was unpopular with some of the shadow cabinet.
Allies of the Labour leader had said that due to the relative inexperience of his team, a candidate who understands how to operate at the top level of government is essential.
Ms Gray’s appointment echoes Tony Blair’s recruitment of diplomat Jonathan Powell while Labour was in opposition in 1995.
Mr Powell later became Number 10’s first chief of staff and played a role in Northern Ireland peace talks before the Good Friday Agreement.
A Labour source said: “[Sue Gray] knows how Number 10 works and she’s very popular with civil servants.”