Downing Street has continued to deny that a lockdown-busting Christmas party took place last year amid new claims that staff took party in a secret Santa.
The new details, reported by The Times, would squarely indicate that any such event was a planed social gathering rather than an impromptu gathering of work colleagues.
The report says staff wore festive jumpers and were asked to bring “secret Santa” gifts to the event, which was organised via a WhatsApp group. They were said to have brought alcohol and food to the event alleged to have been attended by dozens of colleagues on December 18 last year when London was in Tier 3 restrictions banning social mixing indoors
Asked about the reports at a lobby briefing on Tuesday, the prime minister's spokesperson said: "There wasn’t the party as described and the COVID rules were followed.”
When pressed on the Secret Santa, the spokesperson said: “There wasn’t.”
The claims join growing controversy around the party, originally revealed by The Daily Mirror.
Labour has accused the government of "one rule for them, one rule for everybody else" in light of the allegations - with several Labour MPs reporting the party to the police.
The government has repeatedly refused to elaborate on the details of the event, instead insisting that all coronavirus legislation was followed in Number 10 at the time.
Dominic Cummings, Boris Johnson's estranged former special adviser, appeared to confirm the party happened on Twitter, accusing the prime minister of lying.
"V unwise for No10 to lie about this but PM set the course of lying on covid in spring when he decided to start rewriting history, deny herd immunity plan etc," he said on Monday.
"NB some lobby hacks were also at parties in No10 flat so trying to bury this story...".
When Johnson was asked on Tuesday whether the party happened, he said: "I can tell you that the guidelines were followed at all times."
Adding: "What I can also tell you, is that we are focusing on the issues that matter to me, above all - and that is fighting crime, and I believe those are the things that matter also to the British public."
However, the matter continues to be a source of confusion from senior Conservative MPs.
On Sunday, justice secretary Dominic Raab said that the police would not be investigating whether the party broke coronavirus restrictions because it was a year ago - but conceded that a formal party at the time would have broken the rules.
Watch: Raab piles pressure on Johnson to come clean over No 10 Christmas party
And, on Thursday, vaccines Minister Maggie Throup was met with a groaning audience on BBC's Question Time after claiming "all guidance was carefully followed" when asked if the party happened.
Questions over the Secret Santa is another chapter in what is becoming a growing headache for the prime minister amid mixed messaging over the party and the emergence of the new COVID variant, Omicron.
On Tuesday, the prime minister confirmed that the new variant of the virus could be more transmissible than previous strains; scientists previously expressed concerns that Omicron's high levels of mutations could make it more contagious and more able to evade vaccines.
Johnson is set to review the measures they have put in place in response to the new variant, such a mandatory mask wearing on public transport and shops, next week.
Watch: Boris Johnson declines to repeat official denial about staff party at No 10