UK Prime Minister Boris Johnson insisted, time and again, that a gathering around Christmas time last year involving his party aides complied with social distancing requirements at the time.
But a new photograph appears to contradict his comments and could have far-reaching ramifications.
The British PM has faced a barrage of criticism and calls to quit over claims of an illegal Downing Street party on December 18, 2020.
"I understand and share the anger up and down the country at seeing No 10 staff seeming to make light of lockdown measures," he said earlier this month after a video emerged of senior aides joking about a Christmas party at Downing Street.
"I apologise unreservedly for the offence that it has caused... and I apologise for the impression that it gives."
Johnson added he had been "repeatedly assured" that there was no party inside his Number 10 Downing Street office and that no rules were broken.
A photographed published on Wednesday shows Tory aides gathering in Christmas hats and in clear breach of those rules.
On social media, British actor and comedian David Schneider shared the image alongside a picture of an elderly woman communicating with a young boy through a glass window.
In December last year, Christmas lunches and parties that were "primarily social activity" were banned as Britain — one of the worst-hit countries by Covid-19 — battled a surge in cases of the Delta coronavirus strain.
Mixing of more than two people from two households indoors was banned, scuppering Christmas plans for millions after months of tight restrictions, including lockdown.
The claims of double-standards have put Johnson's position under threat at a crucial time.
MPs vote next week on the government's latest proposed restrictions to curb the spread of the Omicron variant, with many Tories unhappy at plans to introduce mandatory vaccine passports.
Johnson also faces a by-election in a safe Tory seat vacated by an MP found to have illegally lobbied ministers on behalf of two companies that had him on their payroll.
A significant rebellion in the House of Commons and either a defeat or substantial loss of majority in Thursday's by-election could see calls for Johnson to go reach fever pitch.
One commentator said the by-election was effectively "a referendum" on his premiership.
The photograph comes after footage emerged of Johnson's aides making jokes about a Christmas party.
The allegations have prompted public fury and damaged Johnson's government, just as the fast spread of the Omicron variant has pushed him to announce stringent new virus restrictions.
London's Metropolitan Police, known as the Met, said in a statement that the force had received "a significant amount of correspondence" on the reported parties and detectives had examined the video footage.
But commenting prior to the release of the latest photograph, police said the material "does not provide evidence of a breach of the health protection regulations" and only "restates allegations made in the media".
"Based on the absence of evidence and in line with our policy not to investigate retrospective breaches of such regulations, the Met will not commence an investigation at this time."
The Mirror reports that 24 people were at the party on December 14 last year.
Among them was billionaire Tory donor Nick Candy and a senior figure in Johnson's election campaign, the publication reports.
The Guardian reports that London mayoral candidate Shaun Bailey was in attendance and has since stood down from an official role in the London assembly.