Britain’s former Prime Minister Boris Johnson resigned his parliamentary seat on Friday, another dramatic twist in the career of one of the country’s most colorful and divisive politicians.

Mr. Johnson has been under investigation from a committee of the House of Commons that was looking into whether he had lied to Parliament over lockdown-breaking parties in Downing Street during the Covid-19 pandemic.

On Friday, having received a confidential copy of their findings, he accused the committee of attempting to drive him out, adding: “They have still not produced a shred of evidence that I knowingly or recklessly misled the Commons.”

The committee had the power to recommend a sanction that could have led to Mr. Johnson being forced to fight an election to hold his constituency just outside London — a contest he might well have lost.

Instead, the former prime minister pre-empted that prospect by quitting. His decision means that there will now be a by-election in the constituency, but one he says he will not contest.