Boris Johnson’s punishment for going to that party will be decided by himself

It may be worth reminding you that the final arbiter of whether Boris Johnson should be punished or sanctioned for allegedly breaking lockdown rules by attending that bring-your-own-booze Downing Street party is not the second permanent secretary at the Cabinet Office Sue Gray - even though she has been given the delicate task of investigating what happened.

Under the British system, the ultimate judge and jury of whether any minister should be punished is the prime minister. And that means only the PM can decide his own fate.

Gray will set out what happened, presumably - in the words of one of her colleagues - “with her admirable clarity”. Another official said of Gray: “It’s normally pretty clear from her reports what decisions need to be taken”.

It comes after ITV News revealed an email proving a party was held in the garden of 10 Downing Street during lockdown 2020.

So let’s hypothesise - in a way that does not stretch credibility - that Ms Gray's report is clear that the prime minister’s principal private secretary Martin Reynolds broke lockdown rules by organising the party and the PM broke the rules by attending it.

In those plausible circumstances, Cabinet Secretary Simon Case and the chief operating officer of the civil service Alex Chisholm would decide whether Reynolds should be sacked or punished in some other way. The disciplinary procedures are civil services procedures (though one possible complication is that Case may be too compromised to adjudicate if it turns out that in December 2020 he was wrong to implicitly sanction a virtual quiz that took place in his office).

They’ll sound out the PM, because Reynolds has such a close working relationship with him. But it is a Whitehall matter.

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By contrast, Case and Chisholm are not the adjudicators for the PM. The judge who has to decide whether the prime minister should be punished is - under the ministerial code - the prime minister himself.

Mr Johnson decides the fate of all ministers who break the rules, including himself. He marks his own homework.

And as you will recall he did not sack the Home Secretary Priti Patel even though his then adviser on ministerial standards found she had breached the ministerial code by bullying officials. Sir Alex Allan quit, in frustration.

So will Prime Minister Johnson sack himself, if Gray’s report is unambiguous that the party he attended was unlawful?

As a Boris Johnson observer for at least two decades, I would argue that stretches credibility.

Johnson could ask Allan’s successor, Lord Geidt, to review Gray’s report and give him a second view. Given that Geidt absolved him of serious misconduct when a party donor bought his wallpaper, this could be a useful device to buy time.

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But it would all be for show. In the end, the PM’s destiny will be determined not by the rules of probity but by raw politics, or what he can get away with.

To put it another way, there is only one group of people who can throw him out before the next election: Tory MPs.

If they think misjudgments like the BYOB party are costing them too much, they’ll send in letters to their de facto shop steward, Sir Graham Brady, stating they’ve lost confidence in him, and a leadership election would follow.

And Tory MPs too will be ruled by pragmatism rather than ethical principle.

Johnson has lost whatever authority he had to order them about like sheep. That will suit a good number of them. So although that drink on May 20, 2020 was the most expensive of Johnson’s life, he doesn’t yet know the bill.