Boris Johnson must explain why he thinks him drinking at a party during a national lockdown was “acceptable”, Scottish Tory leader Douglas Ross has said.

Pictures released by ITV News on Monday show the Prime Minster holding a drink while standing behind a table littered with bottles of wine and food.

Mr Ross said the pictures would make people “very angry”.

The Prime Minister was previously fined for another party celebrating his birthday – along with his wife Carrie and Chancellor Rishi Sunak – but not for the event shown in the pictures, which was a leaving party for former head of communications Lee Cain on November 13 2020.

Eight days before, the Prime Minister had announced another national lockdown as a result of the Covid-19 pandemic.

The Scottish Tory leader has previously called for the Prime Minister to quit over partygate before reversing course, citing the need for stability at the top of government to deal with the Russian invasion of Ukraine.

On Monday, he stopped short of calling for the Prime Minister to leave his post.

Downing Street partygate
The Prime Minister at a leaving party on November 13 2020 (ITV/PA)

“These images will rightly make people across the country very angry,” Mr Ross said in a statement.

“The Prime Minister must outline why he believes this behaviour was acceptable. To most, these pictures seem unjustifiable and wrong.”

A No 10 spokeswoman said the Met had seen the pictures, adding the Prime Minister would not comment until the release of Sue Gray’s partygate report which is expected later this week.

“The Cabinet Office and the Met Police have had access to all information relevant to their investigations, including photographs,” she said.

“The Met have concluded their investigation and Sue Gray will publish her report in the coming days, at which point the Prime Minister will address Parliament in full.”

Scottish Labour leader Anas Sarwar said the Prime Minister has to stand down over the new revelations.

“This proves that Boris Johnson lied to Parliament and lied to the people,” he said.

“He has been taking us all for fools. No more excuses, no more lies, and no more false equivalences – Boris Johnson has to go.”

Scottish Green health spokeswoman Gillian Mackay said the images were “shocking” and “prove that the Prime Minister has lied”.

She added: “They prove that he has lied repeatedly to the public and to Parliament.

“Every day that Boris Johnson remains in office is an insult to the millions of people who made sacrifices and had their lives turned upside down by the pandemic.

“If he had even a shred of dignity or integrity he would have resigned months ago.”

Scottish Lib Dem leader Alex Cole-Hamilton said the pictures “obliterate the Prime Minister’s claims” he did not know about rule breaking at Number 10, adding: “The public are not stupid. They understood perfectly well that the Prime Minister was lying to them. The only people who fell for it were Conservative parliamentarians.”

Mr Cole-Hamilton called on Mr Ross to re-submit his letter of no confidence in the Prime Minister.