Ms Davidson reacted on social media after more evidence of alleged rule-breaking by Downing Street was revealed by ITV, writing on Twitter: “What tf (the f***) were any of these people thinking?”
An email emerged on Monday night showing Mr Johnson’s principal private secretary had invited more than 100 Downing Street staff to an evening gathering on May 20, 2020 when rules meant the public could only meet one other person outside.
UK health minister Edward Argar said he could completely understood why people were “angry, upset and hurt by these allegations”, but they would have to wait for senior civil servant Sue Gray’s internal investigation to be completed.
Referencing Mr Agar’s argument that people should wait until the conclusion of the investigation, Baroness Davidson said: “This line won’t survive 48 hrs.
“Nobody needs an official to tell them if they were at a boozy shindig in their own garden. People are (rightly) furious. They sacrificed so much – visiting sick or grieving relatives, funerals.
“What tf were any of these people thinking?”
Former Conservative attorney general Dominic Grieve said Mr Johnson was a “serial liar” and should be ousted from office after the latest revelation.
Mr Grieve accused the Prime Minister of a pattern of behaviour that is undermining trust, including by lying about potential rule-breaking gatherings at Number 10 during the first coronavirus lockdown.
Multiple reports, including from Mr Johnson’s former adviser Dominic Cummings, have suggested the Prime Minister attended the event with his wife Carrie.
Mr Grieve, a barrister who served as David Cameron’s attorney general from 2010 to 2014, said that Tory MPs who are “very unhappy” with the current Prime Minister’s behaviour should move to replace him.
Asked about the latest allegation of the Prime Minister and Downing Street staff flouting Covid-19 rules, Mr Grieve said: “He ought to be in a lot of trouble because he’s told a series of untruths about these issues over a period of time and the latest evidence clearly suggests that the rules were broken.
“There may be mitigating circumstances for that, I don’t know. But it’s part of a pattern of behaviour by him which undermines trust.
"And because trust is undermined, it then becomes very difficult to accept anything he says on any topic whatsoever.”
Mr Grieve said he thinks the public now has “very little” trust in Mr Johnson and added: “The difficulty we have here is that we have a Prime Minister who’s effectively a serial liar.”
Speaking on the BBC’s Good Morning Scotland programme, Mr Grieve said: “My impression is that there are many MPs who are deeply unhappy about him, but the difficulty is that replacing a prime minister requires courage, it requires the upheaval that goes with it, and it requires the co-ordination necessary to get him removed.
“I think it’d be very desirable if he were removed.
“I think the Conservative Party would find that it has a much better future without him than it has with him at present.
“But whether that’s going to happen in the short-term future, I think is open to doubt. In the longer term, I think that he is going to have great difficulty recovering from these events.”
Mr Johnson has refused to answer questions about the latest allegation of Downing Street rule-breaking, instead claiming the public should wait for the conclusions of an investigation by Ms Gray – a line repeated by Mr Agar on Tuesday morning.
But Mr Grieve said: “I think that ultimately you have to make a judgment about whether somebody is suitable to be a political leader and the prime minister in a democracy.
“I don’t think the current Prime Minister passes that test and I don’t think it requires conclusions from Sue Gray to tell one that.
“Even if he were to escape Sue Gray’s censure, I don’t think it said to make any difference to his long-term behaviour.”
Peter Cardwell, who was a special adviser to four Cabinet ministers from 2016 to 2020, said the Prime Minister was “in serious trouble”.
In an interview on Good Morning Scotland, Mr Cardwell said: “I think he’s a liability. But I also think that the Conservative Party are thinking long and hard about whether to ditch him at the moment”.
Speaking of Ms Gray’s investigation into alleged Christmas parties at Downing Street, Mr Cardwell said: “I’ve absolutely no doubt her inquiry will be comprehensive, and I imagine it will be damning as well.
However, he added: “I think the dogs in the street can see that this is a very straightforward matter”.
While he said he thinks Mr Johnson is in trouble, he also added: “He is someone who has defied expectations and come back from the brink on a number of occasions”.
"He's someone who is very difficult to write off, but it’s also very difficult see how he gets out of this - especially if there are further revelations, and if we’re in a situation where there may well be a police inquiry”.
A spokesman for Scotland Yard said: "The Metropolitan Police Service is aware of widespread reporting relating to alleged breaches of the Health Protection Regulations at Downing Street on May 20 2020 and is in contact with the Cabinet Office."