Mr Ross extended an olive branch to Mr Johnson on Thursday, disclosing he had withdrawn his letter to the 1922 Committee calling for a vote of no confidence.

The Scottish Conservatives also invited the Prime Minister to speak in person at their two-day spring conference. It had previously been expected he would address the event virtually.

His intervention was a huge boost to Mr Johnson’s longer term hopes of riding out the Partygate scandal as Mr Ross was the first senior Tory to demand his resignation.

Mr Ross urged Mr Johnson to quit in January after the Prime Minister failed to convince him in a phone call about why he attended a Downing Street garden party during lockdown. Almost all the party’s 31 MSPs then echoed their leader’s call.

With the immediate threat to Mr Johnson’s position receding as a result of the Ukraine crisis, Mr Ross had been under increasing pressure to explain how he could continue working with the Prime Minister while seeking his removal from office.

‘Now is the time for unity’

The Scottish Tory leader told the BBC: “Now is not the time to try and replace a prime minister – now is the time for unity. The only person who would gain from the removal of a UK prime minister from office would be Vladimir Putin.”

He added: “We should be supporting the Government to support the people of Ukraine, to support the government of Ukraine, because the real threat to everything at the moment is from Vladimir Putin.

“It’s not actions that took place a couple of years ago, serious though they are. It’s the actions that are happening right now, with people dying, children losing their lives and a country being destroyed through no fault of their own.”