Militarising the border with France and abolishing the BBC licence fee may seem an extreme way to win back estranged backbench MPs, but the Prime Minister is in dire straits.

The heaviest burden is therefore on Sue Gray, the second permanent secretary at the Cabinet Office. She has been given the unenviable task of providing an objective assessment of whether lockdown or other rules were broken when Downing Street partied over the past 18 months and who may have been to blame. Her task has been made all the harder over the past three days, following widespread briefing by allies of the PM that the culprits are civil servants and special advisers, and he is in effect an innocent victim.

The PM’s plan, according to those close to him, is to scorch the earth of the supposedly culpable officials – to clear them out – so he can live securely ever after at No. 10. This is shattering morale in Whitehall, as a number of senior civil servants have told me.

‘It feels like utter shit’, said one. ‘It would be seen as completely unfair if we took all the blame and the Prime Minister was let off the hook’.

Another said that the official civil service, whose core function is to provide continuity of effective government whoever is in power, would be seriously damaged. Good people would leave. Recruitment would be harder.

The question, therefore, is how Gray serves the government and the Prime Minister in her report, without betraying the institution that has been her professional life since leaving school.

‘Sue is acutely aware both of the importance of what she is doing, and not to show fear or favour to anyone, including the Prime Minister,’ said one of her colleagues.

In that sense, the briefings from those close to the PM that he did nothing wrong other than trust the flawed advice of officials – and that everyone else is to blame – is highly risky for him. In foreshadowing what many would see as a whitewash, the Prime Minister’s team may have achieved precisely the opposite of what they want.

‘Sue Gray will be defined for the rest of her life by this report,’ said a former minister. ‘She will be aware of that. And in my judgement she won’t like the idea of being remembered as the civil servant who sacrificed her colleagues to save Boris’.