Unparalleled, shocking, unprecedented: A sitting prime minister and his chancellor found by the police to have broken the laws he himself not only set while in office but repeatedly told the public to stick to during the national COVID emergency.

But weeks ago, this would have been an event likely to trigger a confidence vote in Boris Johnson, whose moral and political authority collapsed at the beginning of the year following revelations over successive alleged lockdown breaches in Downing Street.

Instead on Tuesday, when the fixed penalty notices were announced, the vast majority of the parliamentary Conservative party kept their counsel, while the cabinet came out in support for Mr Johnson and Rishi Sunak. Mr Johnson appears to have defied political gravity yet again.

The primary reason for this swing in fortunes is the war in Ukraine. The popular refrain – even from those who were openly hostile to Mr Johnson just a few weeks back – is ‘now is not the time’.

The PM is considered by his MPs to be having a ‘good war’ and attempting to remove him in the midst of the biggest conflict in Europe in generations would be against the national interest.

For all Mr Johnson’s shortcomings, Putin is the enemy and the party and country should remain united against this external aggressor, however frustrated they may feel with the PM.

There is also the looming matter of the local elections on 5 May. One former cabinet minister told me on Tuesday colleagues were anxious about sparking a confidence vote ahead of polling day – divided parties don’t win elections – and would want to try to keep a lid on internal splits until the ballot box moment has passed, although a dire performance will undoubtedly put further pressure on the PM in a few weeks’ time.

Fine could be the tip of the iceberg for Boris Johnson

There is also the matter of who else if not Mr Johnson? Rishi Sunak, until recently the prince over the water has suddenly been recast as more of a lame duck following his politically dire Spring Statement, the damaging revelations of his wife’s non-dom status and his own COVID lockdown fine. A key challenger removed will make MPs even more nervous about trying to oust the man they’ve already got.

But that doesn’t mean the prime minister is not going to come under considerable pressure in the coming weeks. Sustained poor polling and negative headlines, dire election results and further revelations are all points of real danger.

For this fine could be the tip of the iceberg for Boris Johnson. The fines issued to the PM and chancellor over Mr Johnson’s birthday gathering in Downing Street on 19 June 19 is but one of up to six events being investigated by the Met that the PM’s been linked to. There could well be more fines for him on the way for events such as the 20 May 2020 garden party at No 10 where staff were invited to bring their own bottle.

As Catherine Haddon of the Institute of Government pointed out on Tuesday, the birthday cake gathering “was perhaps the one [event] that seemed hardest to rule on”.

“So the police have decided it did breach COVID law which suggests more fines coming for other events.

“More fines could become very politically difficult for the PM who sought to portray his transgression on 19 June as an exceptional event when in time it could turn out as one incident in a pattern of breaches.”

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There is also the matter of Sue Gray’s report. The senior civil servant who led the investigation and gathered the evidence that triggered the Met investigation, has said she will publish her report when the police have concluded their work.

What might she say about the PM’s conduct and what he knew when?

Mr Johnson has insisted throughout that he did not realise lockdown rule were being breached. If the Sue Gray report concludes that aides did warn Mr Johnson that a party was in breach of lockdown rules (his former advisor Dominic Cummings says the PM was warned over the 20 May garden party), then the PM will have misled parliament. And that is a moment of acute danger for him.

And even if MPs can save the PM in the short-term, what about the people who really matter – the voters? Will his personal polling ratings plummet? Will voters forgive Mr Johnson or refuse to forget? Will the vote-winning PM become a drag anchor on the Tory brand?

Tuesday was momentous. April 12 was the day Boris Johnson became the first sitting PM – to the best of our collective knowledge – to be found to have broken the laws (he himself created).

And yet he goes on – for now. But will he lead the Conservatives into the next general election? On that, the jury still out.