Rory Stewart has announced that he will not be re-standing as an MP at the next election and that he is also resigning his membership of the Conservative party.
That Stewart is going underlines how much things have changed in the party since the leadership election. He was one of the contenders, and stayed in that contest far longer than many had expected. Having pitched to lead the party, he has now left it just months later. And he is not the first to leave: Sam Gyimah defected to the Liberal Democrats after having the Conservative whip removed, though Gyimah was never considered a serious contender in the race (in fact his entry into it was what prompted the party to tighten up its rules as there were so many candidates who clearly didn't stand a chance).
This week Boris Johnson pitched his party as a One Nation Conservative party. A number of figures had continued to make the case for the 21 MPs who were ejected from the parliamentary party to be allowed a way back, but Stewart has decided that he doesn't want to take that. Indeed, it is one thing to offer some kind of return for the contrite, and another to make the party feel as though there is a real place for those with Stewart's politics.
One of the reasons Johnson was content to push the stand-off with these MPs was that it meant the Conservative party will not be divided over Europe at the next election. After decades of Tory leaders trying to straddle the split in the party, Johnson decided to solve it by removing one half of the split. Why would Stewart and others want to return to campaign on a manifesto that they fundamentally disagree with?
But is this really the end of Stewart as a politician? He's had such a varied life pre-parliament that it often seemed that winning the Tory leadership contest would only rank in the top five interesting things he'd done in his career. It is conceivable that he could go off and do something else entirely. Or, given that it was going to be difficult for him to win his Penrith seat as an independent, it might not be a huge surprise if he pops up in another constituency at some point.
Update: As I predicted, this isn't the end of Stewart's time in politics. He has told his local paper that 'I hope to start work in another part of the country' and that he will 'stay involved in politics'.