Allies of former British prime minister Boris Johnson have reacted furiously as partygate investigator Sue Gray plans to join Labour leader Keir Starmer's office as his chief of staff.
The Labour leader was "delighted" that the senior civil servant plans to "accept the role subject to the normal procedures", his party said.
The circumstances of her resignation as second permanent secretary in the Department for Levelling Up, Housing and Communities - accepted with "immediate effect" today - will be reviewed.
Ms Gray's investigation into law-breaking parties held in Downing Street during Mr Johnson's leadership played a key role in his downfall as prime minister.
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."
Under the Civil Service code, officials of Ms Gray's seniority must wait a minimum of three months before taking up outside employment.
The move will be scrutinised by Parliament's anti-corruption watchdog, the Advisory Committee on Business Appointments (Acoba), before advising the Prime Minister on whether the move is "unsuitable".
Rishi Sunak will make the final ruling over the rules. Acoba does not have the power to block an appointment.
Arch Johnson loyalists were outraged after Sky News first reported the move, with Jacob Rees-Mogg saying: "So much for an impartial Civil Service, the Gray report now looks like a left wing stitch up against a Tory Prime Minister."
Nadine Dorries, who served as Mr Johnson's culture secretary, described the Gray report as a "stitch up" and said the reported move to Sir Keir's office was "not surprising".
Bassetlaw MP Brendan Clarke-Smith said he was "genuinely shocked", and accused Sir Keir of having "scant regard for the public image of the civil service and the damage this will do".
"After the events of last year, people will quite understandably be questioning the appropriateness of this appointment, including issues of impartiality," the MP added.
Workington MP Mark Jenkinson said: "All part of the plan?"
The Institute for Government think tank's Alex Thomas said the move would be "difficult for the Civil Service", saying it would give "critics a stick".
"Tricky development for those defending impartiality," he added.
A Cabinet Office spokesman said: "We are reviewing the circumstances under which she resigned."
Ms Gray got the job as partygate enforcer after Cabinet Secretary Simon Case had to step down from the investigation when he became embroiled in claims of partying during the pandemic.
Published in May last year, her investigation detailed how officials drank so much they were sick, sang karaoke, became involved in altercations and abused security and cleaning staff.
She criticised "failures of leadership and judgment" in No 10 and said "the senior leadership at the centre, both political and official, must bear responsibility".
Six weeks later, Mr Johnson was forced out of office by his own cabinet and Conservative MPs.
Today a No 10 spokesman said: "I can confirm Sue Gray has resigned from the post of second permanent secretary in the Department for Levelling Up, Housing and Communities.
"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. But you asked me specifically when, that took place this afternoon."
Asked whether there were concerns about unpublished partygate details being passed to the opposition, the spokesman said: "All civil servants leaving the civil service have to abide by the Acoba process."
Labour has not commented on whether Ms Gray has been appointed, but earlier in the day a spokesman said "the process is ongoing, nobody has been offered the job".
