Boris Johnson is expected to blame Simon Case for the lockdown-breaking party culture in Downing Street in a desperate effort to save his own job. The report could prove more damaging for Johnson than the fine he received in April.

Senior officials are braced for Case to be heavily criticised in the report, and are unsure whether he will resign or be sacked by Johnson. If Case were to lose his job, it would mean that the prime minister would keep his job.

According to numerous sources, Sue Gray’s long-awaited findings will single out Case, the UK’s most senior civil servant, for permitting a drinking culture to emerge in which rule-breaking parties became frequent during lockdowns.

According to one senior Whitehall source who has seen portions of the report, it could be much more damaging to Johnson than the punishment he received in April for attending his own birthday party, because it would reveal the PM’s participation in a number of other gatherings that may have violated rules but for which he was not charged.

“It will be the real deal, based on my expectation.” the Whitehall source added ” There will be plenty of it. There will be evidence. She’ll say things like this is under your watch, this is your house,” the person predicted.

Senior officials expect Case to be strongly chastised to the point where he will have to retire or be fired by Johnson in order for Johnson to claim that he responded forcefully and learned lessons.

“That’s probably why he [Case] is still there [and hasn’t been relocated yet],” one source speculated.

Gray is expected to name Johnson and Case, along with about a dozen other officials, in her report into Downing Street parties. It is expected that the report will be hard to survive without someone senior falling on their sword.