A host of Conservative MPs rounded on former official Sue Gray after she quit an impartial civil service role to take up a job with the opposition Labour Party.

Gray — a long-standing senior official who led the investigation into lockdown-busting gatherings under Boris Johnson’s government — stunned Westminster last week by resigning in favor of the high profile gig as chief of staff to opposition boss Keir Starmer.

The move came under attack in the House of Commons Monday as Tory MPs — many of them allied to Johnson — sought to cast doubt on her integrity.

“Does this not smash to pieces the idea of an independent civil service, when we know that one of the most senior civil servants in the country was conniving in secret meetings with the party of opposition,” former Conservative Cabinet minister Jacob-Rees Mogg said.

And he suggested the Partygate probe was conducted by a “friend of the socialists.” Johnson himself sought to use the Gray appointment last week to take a dig at the investigation which contributed to his downfall.

Responding for the government, Paymaster General Jeremy Quin also accused the opposition of “playing fast and loose” with the civil service’s reputation for impartiality, the furthest any minister has gone in criticizing the gig.

Gray’s move remains subject to clearance from revolving-door watchdog ACOBA, although the watchdog’s advice is unenforceable.

Quin told the Commons that he believed Labour may have broken ACOBA’s rules with the “exceptional and unprecedented” appointment.

“The rules state that approval must be obtained prior to a job offer being announced. The Cabinet Office has not, as yet, been informed that the relevant notification to ACOBA has been made,” he said.

“The party opposite talks about rules, they talk about transparency, they talk about standards in public life. Given all the constant talk, it’s time they walked the walk,” he added.

The timing of the process that saw Gray offered the job is under close scrutiny. On LBC radio Monday morning, Starmer refused to specify when he had offered Gray the position.

But he said he had “absolutely no contact” with Gray while she was preparing the Partygate report.

Starmer’s deputy Angela Rayner accused the government of using parliamentary time to “indulge the conspiracy theories of the former PM and his gang.”