It is a week since the Daily Mirror first published reports about parties held in Downing Street last year which may have breached COVID rules.
Although the prime minister has refused to deny parties took place, he has repeatedly insisted guidance was followed at all times.
But new leaked footage broadcast by ITV News, has drawn that account into question.
This timeline brings together the dates on which the gatherings took place, and what ministers, government spokespersons and Boris Johnson himself have said since.
27 November 2020
Boris Johnson gives a speech at a leaving party for a member of staff in Downing Street during the second national lockdown, according to reports in the Daily Mirror.
16 December 2020
Tier 3 restrictions come into effect in London, meaning people were not allowed to mix indoors with anyone outside their household or support bubble.
18 December 2020
A party takes place in Downing Street with around 40 people in attendance, according to sources who have spoken to Sky News. The party was organised via WhatsApp, with staff encouraged to bring “Secret Santa” presents, according to The Times.
22 December 2020
As staff in Downing Street prepare to launch daily press briefings in a new custom-built media room, Boris Johnson’s then-spokeswoman Allegra Stratton takes questions from colleagues as part of a rehearsal.
During the rehearsal Number 10 special advisor Ed Oldfield poses a question about a party that took place in Downing Street a few days earlier.
The rehearsal is being recorded.
30 November 2021
The Daily Mirror publishes a story revealing the events that took place in Downing Street on both 27 November and 18 December the previous year, prompting denials that COVID rules were broken.
1 December 2021
The prime minister was asked about the party by Labour leader Sir Keir Starmer at PMQs. Mr Johnson does not deny a party took place but tells MPs “all guidance was followed”.
Sir Keir responds by saying: “Does the prime minister really expect the country to believe that while people were banned from seeing their loved ones at Christmas last year, it was fine for him and his friends to throw a boozy party in Downing Street?”
He accuses the PM of “taking the British public for fools”.
2 December 2021
Vaccines minister Maggie Throup faces ridicule for this answer to questions about the Downing Street parties on BBC Question Time: “I have been reassured that all guidance was carefully followed as it continually is… Whatever the event was, the guidance was followed… this has been just rumour and hearsay.”
5 December 2021
Justice Secretary Dominic Raab tells the BBC’s Andrew Marr: “The PM’s very clear no rules were broken. I wasn’t there by the way.”
He adds: “If anyone held a party contrary to the rules, of course, that’s the wrong thing to do.
“As a lawyer and as a politician, it’s not a responsible thing to start answering hypothetical questions about anonymous sources in relation to unsubstantiated claims.”
6 December 2021
In response to reports in The Times that the party on 18 December 2020 was organised on WhatsApp and involved a ‘Secret Santa’ game, the prime minister’s official spokesman says, “there was not a party and the COVID rules were followed at all times”.
Policing minister Kit Malthouse tells Sky News: “We are assured, I’ve been assured, that everything was done to comply with COVID regulations at the time… my general view is that when crime is reported it should be investigated”.
7 December 2021
In a short interview clip with reporters Boris Johnson once again refuses to deny a party took place, but says: “I’ve satisfied myself that the guidelines were followed at all times.”
Later that evening, ITV News broadcast video of Allegra Stratton’s rehearsal from 22 December last year.
The Metropolitan Police issue a statement saying: “We are aware of footage obtained by ITV News relating to alleged breaches of the Health Protection Regulations at a Government building in December 2020. It is our policy not to routinely investigate retrospective breaches of the COVID-19 regulations, however the footage will form part of our considerations.”
Downing Street then issue a fresh response: “There was no Christmas party. COVID rules have been followed at all times.”