Boris Johnson has stepped down as an MP with immediate effect.
The former Prime Minister quit after receiving a report on the Partygate scandal. Johnson accused a Commons investigation of attempting to 'force' him out.
In a statement, Johnson said he is standing down - triggering an immediate by-election - because he is "bewildered and appalled" at the Privileges Committee's investigation into him and whether had had misled parliament over Partygate.
He said he had received a letter from the committee "making it clear, much to my amazement, that they are determined to use the proceedings against me to drive me out of Parliament".
He said: "I have today written to my association in Uxbridge and South Ruislip to say that I am stepping down forthwith and triggering an immediate by-election.
"I am very sorry to leave my wonderful constituency. It has been a huge honour to serve them, both as mayor and MP."
He added: "It is very sad to be leaving parliament, at least for now, but above all I am bewildered and appalled that I can be forced out, anti-democratically, by a committee chaired and managed, by Harriet Harman, with such egregious bias."
Johnson also used his resignation statement to criticise Rishi Sunak's Government.
"When I left office last year the government was only a handful of points behind in the polls. That gap has now massively widened," he said.
"Just a few years after winning the biggest majority in almost half a century, that majority is now clearly at risk. Our party needs urgently to recapture its sense of momentum and its belief in what this country can do.
"We need to show how we are making the most of Brexit and we need in the next months to be setting out a pro-growth and pro-investment agenda. We need to cut business and personal taxes - and not just as pre-election gimmicks - rather than endlessly putting them up. We must not be afraid to be a properly Conservative government.
"Why have we so passively abandoned the prospect of a Free Trade Deal with the US? Why have we junked measures to help people into housing or to scrap EU directives or to promote animal welfare?
"We need to deliver on the 2019 manifesto, which was endorsed by 14 million people. We should remember that more than 17 million voted for Brexit. "
It comes as a number of senior officials who were implicated in Partygate have been nominated in Johnson's resignation honours list.
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