Boris Johnson is confident Tory rules will not be changed to give MPs another chance to oust him within months because doing so would weaken the position of any potential successor, allies said.

The Prime Minister survived a confidence vote on June 6, but 41% of his own MPs tried to remove him.

The rules of the Tory 1922 Committee mean there cannot be another confidence vote within 12 months, although Mr Johnson’s opponents could attempt to lift that restriction.

If the rules were changed, every leader for evermore would have a gun to their head

But allies of the Prime Minister said making it easier for backbenchers to get rid of the leader would permanently damage the party.

“If the rules were changed, every leader for evermore would have a gun to their head,” a source close to Mr Johnson said.

“They would never be able to get on with anything, as they would be constantly beholden to the whims of MPs.”

The Prime Minister’s allies are becoming increasingly frustrated with vocal criticism from former party leaders who failed to win general elections, including Lord Hague and Lord Howard.

Although those around Mr Johnson are confident the threat of another confidence vote has receded, the Prime Minister still faces the prospect of a potentially damaging parliamentary investigation into whether he lied to MPs over the partygate row.

The Privileges Committee inquiry that could determine Mr Johnson’s fate in office began on Wednesday with a decision to allow Downing Street staff to give evidence anonymously if necessary.