The moment of maximum danger for Boris Johnson will be the verdict on whether he lied

Boris Johnson hosting a cabinet meeting at Number 10 Downing Street on Tuesday. Credit: PA

Much as Boris Johnson wants to "bash on", deliver popular populist policies, and characterise Monday's confidence vote as the catharsis that purges him and his party of the partygate poison, his struggle to re-establish his credibility and authority will be the challenge of his life.

First of all, most of the 148 Tory MPs who rejected him cannot be bought off, because they typically want him out not for the policies he espouses but rather for what they see as his character flaws - and they are doubtful he can change his spots.

I asked one rebel what was the new plan, after the rebels failed to muster the 180 votes needed to unseat him. The answer: "A process for securing 30 extra votes."

A few rebels have said today that they will try to bury their qualms and do the unity thing. A hard core of them are biding their time.

This fills some of those close to Johnson with the most profound gloom. "It will end very badly," said one minister.

Boris Johnson addressing cabinet ministers on Tuesday. Credit: PA

So the next existential threat to the PM (forgive the cliche) will be the verdict of the Privileges Committee investigation into whether Johnson willingly and knowingly lied to Parliament when he told MPs there were no illegal parties and no Covid rules were broken.

Even those Tory MPs who are the PM's greatest fans concede the evidence looks bleak for him.

And although the ministerial code of conduct is widely seen to have had some of its sharper teeth removed with a redraft, it still says in terms that any minister who knowingly lies to parliament is expected to resign.

If it is found that the PM did deliberately lie to Parliament, he will struggle to survive - a test which will come in the autumn, as Robert Peston explains

So if the Privileges Committee concludes he lied on purpose, but Johnson continues to insist it was an accident, what then?

The code's entire authority stems from the power of the premier, as the sole individual who can enforce it.

So the PM would have to decide to ignore his own protestations of innocence and sack himself on the basis that the Privileges Committee did not believe him.

Would he really do that?

And by the way, is it healthy that such an important set of rules for ensuring we're governed honestly and decently are only as effective as the determination of any prime minister to enforce them?

But even if the PM were to reject the Privileges Committee verdict, that would not be the end of the matter.

Because any such verdict, including a possible sanction, has to be endorsed by the full House of Commons, either "on the nod", without a formal vote (the norm), or with a vote.

Let's say there's a vote to suspend the PM from the Commons, possibly for just a single day, for the crime of lying.

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That really would be the ultimate humiliation for any premier. "It would be curtains for Boris," said a Tory MP who has seen leaders come and go over a few decades.

It all means that the next time the Tory rebels have a chance to throw out the PM, perhaps, will be that expected vote - probably in early November - to confirm whether Johnson lied by design or because the fates conspired against him.

And although the government has a healthy working majority of 75, it would shrink to minus one if just 38 Tory MPs were to vote with the opposition.

Yesterday Boris Johnson saw 148 of his colleagues vote for the chaos of a leadership election rather than keep him in Number 10. Most of them won't be swayed by appeals to be loyal to the leader and party. Also, votes on Privileges Committee reports are supposed to be conscience votes for MPs, not votes whipped along party lines.

To put all this in the nutshell, the moment of maximum danger for Johnson is yet to come and will be that formal Commons judgement on whether he is a liar.