Boris Johnson is “on probation” and could still be removed from office if he fails to win back the trust of Tory MPs, a former minister has said.

Lord Ian Duncan, who served in various ministerial posts under Theresa May and Boris Johnson after he entered the House of Lords in 2017, said the Prime Minister “has a task to do” after 148 of his MPs voted in favour of his removal in a confidence vote on Monday, admitting the chances of the Prime Minister continuing for a long time were “slim”.

The Prime Minister won the vote, which was called after 54 MPs submitted letters of no confidence to the backbench 1922 Committee following the release of the Sue Gray report which detailed a number of gatherings in Downing Street during the pandemic, one of which resulted in a police fine for Mr Johnson, his wife and Chancellor Rishi Sunak.

“He’s got a task ahead of him right now, he is on probation,” Lord Duncan told BBC Scotland’s Sunday Show.

“If he fails that probation, the Tory party will do what it always does with leaders who are not delivering – they will remove him.”

When asked if the Prime Minister was a “lame duck” as a result of Monday’s vote, the former MEP said: “He probably is in troubled waters.

“If you can make people, almost, forget what has happened over the last few months, then he has a slim chance of carrying on, but I would have thought that would be very slim.”

The Conservative Party, Lord Duncan said, was “quite mercenary” when it comes to removing party leaders they deem to no longer be up to the job.

“Over the past 20 years, when a leader has not been able to do what they were meant to do, the Tory Party don’t stab them in the back – they stab them in the face,” he said.

“If they’re not delivering – they are removed.”

The Tory peer also defended the decision of Scottish leader Douglas Ross to again reverse course and vote for the removal of the Prime Minister.

Mr Ross, who initially supported Boris Johnson’s premiership, called for his resignation after reports of Downing Streets parties surfaced, submitting a letter to the 1922 Committee.

But when Russian invaded Ukraine, Mr Ross rescinded his letter and supported the Prime Minister’s position, stating the need for stability at the top of government to deal with the war, before voting along with all but two of his Scottish MPs to remove the Prime Minister on Monday.

“The important thing is that Douglas Ross got it right when it mattered,” Lord Duncan said.

“When it mattered he cast a vote for what he deemed to be right, he did so against the Prime Minister – the leader of a party he has belonged to for many years, that itself is a good sign.”

Lord Duncan’s comments come as the former head of communications for the Scottish Tories Andy Maciver called for the Scottish incarnation to distance itself from the UK party and set up a separate group.

“A political party which has no relationship to the Tory party, formal or informal, and has no involvement in elections to Westminster,” he wrote in the Herald on Sunday.

“A political party which is unimpeachably Scottish. A political party which, in time, could play a role in unsticking Scottish politics, normalising us and, dare I say, Europeanising our political party structures.

“A new political party is not a ready meal. It needs to be prepared and then cooked, and it needs a good amount of resting time before it is ready to be enjoyed.

“However, since the alternative is not eating at all, the choice should be fairly clear.”