Why is there a row in the UK about Boris Johnson and Christmas parties?

Why is the British prime minister, Boris Johnson, in so much trouble?

On Tuesday last week, the British tabloid newspaper, the Mirror, published a story that claimed parties had been held at Johnson’s Downing Street residence in the run-up to Christmas last year.

One of the events was said to have taken place on 18 December, with dozens of people drinking wine and playing party games.

There was one major problem with this: London had just been placed under new restrictions to stop the spread of coronavirus. Last December, Covid was spreading rapidly, hundreds of people were dying every day, and Johnson’s government had told people that parties were no longer allowed.

Government guidance at the time stated: “Although there are exemptions for work purposes, you must not have a work Christmas lunch or party, where that is a primarily social activity and is not otherwise permitted by the rules in your tier.”

When Johnson was first questioned about the claims of the pre-Christmas party last week, he denied any rules had been broken. Repeatedly. In media interviews over the last week, a number of his cabinet colleagues have also categorically denied that a party took place, or that rules were broken.

But the explanations did not make complete sense. The BBC correspondent Ros Atkins captured the inconsistencies in this short film.

So, what changed?

The story appeared to be fizzling out – until Tuesday evening. A British broadcaster, ITV News, was leaked a video. The footage showed Downing Street officials doing a practice press conference. It was filmed on 22 December last year – just a few days after the party was said to have taken place.

In the film, Allegra Stratton, a senior political adviser who then worked directly for Boris Johnson, was fielding questions from colleagues – one of them, Ed Oldfield, referenced a party that had taken place days before.

Oldfield asked her: “I’ve just seen reports on Twitter that there was a Downing Street Christmas party on Friday night, do you recognise those reports?”

What followed was revealing and excruciating.

Stratton appeared floored and flummoxed.

Between hesitations and some embarrassed laughter, she replied: “I went home … hold on, hold on, erm, err … What’s the answer? … This fictional party was a business meeting [laughs] and it was not socially distanced.”

Related: Allegra Stratton steps down from Cop26 role after Christmas party video

The video could not have shown Stratton and other officials in a worse light, given the seriousness of the situation facing the UK last Christmas. But worse than that – their conversation appeared to confirm there was a party in Downing Street, despite Johnson’s denials.

How did Johnson react?

To begin with, there was an eerie silence from Downing Street. Usually, government ministers are dispatched to do interviews for the national broadcasters for their morning news bulletins and chatshows.

On Wednesday, they all stayed at home.

All eyes were then focused on prime minister’s questions – the weekly event in the House of Commons where the leader of the opposition Labour party, Sir Keir Starmer, gets to ask Johnson a series of questions.

This week, Johnson started the session with a dramatic apology. Before taking any questions from Starmer, the prime minister told the Commons he was “also furious to see that clip”.

“I can understand how infuriating it would be to think that the people who have been setting the rules have not been following the rules,” he said.

“I apologise unreservedly for the offence that it has caused up and down the country, and apologise for the impression that it gives.”

Johnson insisted he had no personal knowledge of any party, saying: “I repeat that I have been repeatedly assured since these allegations emerged that there was no party, and that no Covid rules were broken.”

This last statement drew jeers of incredulity from opposition MPs. And there was an awkward silence from MPs in Johnson’s Conservative party.

Johnson said he had asked the country’s most senior civil servant. the cabinet secretary, Simon Case, to investigate the claims about the party – and the prime minister promised that anyone found to have broken the rules would be disciplined.

Observers were quick to point out that Johnson appeared to be putting his own staff in the firing line. Had they lied to him about the party? Is it conceivable he didn’t know what was going on?

How damaged is Johnson?

The “apology” is the latest in a series of wretched episodes for Johnson and his party. Over the last few weeks, the Conservatives have been embroiled in a sleaze scandal, provoked by Johnson.

The prime minister intervened to try to stop a Conservative MP, Owen Paterson, from being disciplined after a watchdog ruled he had broken rules by lobbying for a company for which he was working.

Johnson tried to save Paterson by ripping up the House of Commons disciplinary process. This was regarded as an outrageous attempt to stop someone he knew from being punished. The anger this provoked led him to perform a U-turn – but the damage was done.

And now this.

So far, voters have shown remarkable tolerance for Johnson’s looseness with the truth. But there are signs that people outside parliament, and his own MPs within it, are beginning to have second thoughts. Johnson’s position should be strong.

In the 2019 general election, he won a convincing victory. The Conservatives won 365 seats out of a possible 650 – giving the prime minister a clear 80-seat majority.

But the Conservatives are notoriously ruthless when it comes to changing their leader – and Johnson is nothing like as popular within his own party as you might imagine. If MPs conclude he has become a liability, then he is in trouble.

And that’s before Covid is put in the equation. With the UK facing a new Omicron wave of infections, the government may be forced to introduce new restrictions – possibly within days.

Yet how will the country react now that it seems Johnson’s own team have not played by the rules they have set?