The leader of the Scottish Conservatives has said there was a “party of sorts” at Downing Street after Boris Johnson denied there was any such event.
It comes as leaked footage shows the Prime Minister’s aides joking about a festive gathering at No 10 on December 18.
Douglas Ross told STV News: “From what I’ve seen, there was a party of sorts.”
“[Boris Johnson] said there wasn’t a party.
“There was a party of sorts, I wasn’t involved, I wasn’t invited, I wasn’t there but just look at what we’ve seen since then, there was a party of sorts and that was against the guidance last year.
“If people within Downing Street did not follow their own advice then the appropriate action and strong action must be taken.”
Ross admitted Boris Johnson’s handling of the situation in the previous week had damaged the coronavirus public health messaging which he said was the “biggest threat”.
“I’m angry at the way this has been handled because people just want honesty from their politicians and from their government,” he told STV News.
At PMQ’s on Wednesday, Johnson said he had asked the cabinet secretary to conduct a full investigation into the situation but that no party happened.
The Prime Minister apologised and said he was “sickened and furious” by the video of senior aides laughing about a “cheese and wine” night.
Baroness Ruth Davidson, former Scottish Conservative leader, said: “None of this is remotely defensible. Not having busy, boozy not-parties while others were sticking to the rules, unable to visit ill or dying loved ones.
“Nor flat-out denying things that are easily provable. Not taking the public for fools.”
Some reports claimed the evening on December 18 last year featured alcohol and “secret Santa” present-giving, when London was under strict lockdown conditions.
Nicola Sturgeon told STV News that the timing of the alleged party at No 10 was crucial with the dates “engraved” on her mind.
She said December 18 was “one of the most difficult points in a really tough year” and that there was “a very, very serious question mark over the truthfulness of Boris Johnson’s statements on this issue”.
The Prime Minister has denied there was any party or that any Covid rules were broken.
He said he had instructed the cabinet secretary Simon Case, the UK’s most senior civil servant, to investigate the allegations.
Insight: Colin Mackay, STV News’ political editor
Douglas Ross put the boot into Boris Johnson today.
The Scottish Conservative leader accepts that “there was a party of sorts”, and that it leaves the Prime Minister with “serious questions to answer”.
Boris Johnson struggled at Prime Minister’s Questions for the second week in a row on the Downing Street Christmas Party scandal, and Douglas Ross accepts that it could yet bring Boris down.
Sir Keir Starmer forced the Prime Minister to accept that he would hand over the findings of a hastily ordered inquiry by the cabinet secretary to the Metropolitan Police.
Ian Blackford said the Prime Minister had lost the trust of the people and should resign, but their criticism in the House of Commons was a bit overshadowed by a much bigger double act: Ant and Dec destroyed the Prime Minister on I’m a Celebrity last night.
But Ross’ take on the scandal is probably the most damaging for the Prime Minister.
He is the most senior Conservative to question Johnson’s ability to lead his party and the country through this.
Johnson’s poll ratings were already through the floor after the sleaze scandal and his bizarre Peppa Pig speech – this will further undermine the foundations of his premiership.
Which poses the question: Is it enough to bring him down?