How much has Boris Johnson been fined over rule-breaking Downing Street parties?

Boris Johnson is expected to make a “full-throated apology” to MPs on Tuesday after he was fined by the Metropolitan Police for attending a birthday party thrown in his honour during England’s first Covid-19 lockdown.

It is thought the prime minister is unlikely to address any other social events he may or may not have attended at Downing Street or Whitehall between May 2020 and April 2021 during his speech.

A dozen of these have been under investigation by the Met since late January when senior civil servant Sue Gray handed over the evidence she had accumulated over the course of her own inquiry into “Partygate” to Scotland Yard.

Instead, Mr Johnson is expected to insist before the House of Commons that his refusal to resign after being found to have broken the law and seemingly misled both Parliament and the British public about the affair does not amount to a damaging constitutional crisis but is actually a relatively trifling matter in the broader context of the war in Ukraine.

The PM’s defenders have insisted over the course of the last week that it is “not the time” for Britain to undergo a change of leadership because of the need to present a united front against Russian aggression in Eastern Europe.

The cost of living crisis and the problem of illegal immigration via the English Channel, which last week prompted the government to sign a detenion deal with Rwanda, are also thought to be likely topics in the PM’s appeal to hostile members returning from their Easter recess.

But, try as he might, Partygate refuses to go away.

It was reported over the weekend that Mr Johnson had not only attended another leaving do for his former communications chief, Lee Cain, on November 13 2020 but had actually personally instigated the event.

Downing Street declined to comment on those claims.

A week ago, the PM, his wife Carrie Johnson and his chancellor, Rishi Sunak, were all issued with £100 fixed-penalty notices (FPNs) by the Met after investigating officers concluded that they had all been present at a birthday bash for Mr Johnson in the Cabinet Room on 19 June 2020 when strict restrictions concerning social distancing were in place nationwide to contain the first wave of coronavirus infections.

Those fines were reduced to £50 in each case as the recipients paid them off within 14 days, in accordance with the law.

Given that he is thought to have attended as many as five other gatherings during the period under investigation, he could ultimately face more fines, potentially of a cumulative value of more than £12,000 in the worst case scenario.

The amount of each fine doubles with every new offence, a strategy intended to deter repeat offenders from breaking lockdown.

They are set at the appropriate rate for the date on which the offence in question was committed.

So, of the five outstanding parties Mr Johnson is alleged to have attended, one was held before September 2020 and four were after, when fines for breaches had been doubled as part of a government crackdown.

For the one party before September 2020, the fine for a second offence would be £200.

But after that date, a fine for a second offence was £400, a third was £800, a fourth was £1,600, a fifth was £3,200 and a sixth was £6,400.

Assuming Mr Johnson were to be found guilty of six offences in all, that would mean his receiving £12,300 in FPNs (although he could end up paying just £6,150 of that so long as he coughs up within two weeks of receipt).

But the rolling waves of bad publicity and ill feeling further fines would create could conspire to make his position untenable, particularly if the public chooses to punish the Conservative Party at the ballot box in next month’s local elections.

Senior Tory Sir Roger Gale argued on Monday that a “war cabinet” could be established under an “interim administration” led by deputy PM Dominic Raab in the event of the PM stepping down to ensure that the UK’s support for Ukraine is not interrupted by a leadership contest.

However, Mr Johnson is nothing if not an adept escape artist, experienced at brazening out intense storms of criticism and unlikely to go without a fight, no matter how loudly the opposition calls for his removal.