LESS than three months ago, Rory Stewart was vying to become the UK’s next Tory Prime Minister, but yesterday morning he quit the party and announced that he’d be standing as an independent in next year’s race to become Mayor of London.

Stewart announced his resignation first, saying it had been a “great privilege” to serve as the MP for Penrith and the Borders for the last ten years.

Two hours later he revealed that he was running for the top job in London’s city hall.

It’s not clear if he’ll have enough support to unseat Labour’s Sadiq Khan as Mayor, but it’s likely that he’ll take enough votes to effectively end the ambitions of Tory candidate Shaun Bailey.

Yesterday afternoon Ladbrokes put the incumbent on 4/6, Stewart on 2/1, and Bailey on 8/1.

The National: He has previously denied serving for MI6He has previously denied serving for MI6

In a video on his Twitter feed, Stewart, who was expelled from the Tories in the Commons with 20 other Brexit rebels last month, said: “I’m leaving that gothic shouting chamber of Westminster.

“I’m getting away from a politics which makes me sometimes feel as though Trump has never left London and I want to walk through every borough of this great city to get back to us on the ground.”

In an interview with London’s Evening Standard, he added: “It’s always difficult to run against your own party. It’s been a painful journey for me. I suppose it was really crystallised when I had the Conservative whip removed.

“I’ve been proud to be a member of the Conservative Party. There are many values I share with it. I parted company largely over Brexit and the tone of the party, which has become increasingly aggressive.”

He has also written an open letter to Londoners in the paper, saying he will make a stand against the “mutual insults ... lazy habits, half-baked ideas and pointless compromises” of party politics.

Bailey, said he welcomed “any candidate’s decision to stand and hold Khan to account over his woeful record in London”.

The National: Rory Stewart will try and topple Sadiq Khan Rory Stewart will try and topple Sadiq Khan

Labour leader Jeremy Corbyn tweeted: “Rory Stewart wholeheartedly backed Tory cuts that have ripped the heart out of our communities and done so much damage to our police, NHS and schools. He would be a disaster for London.”

The SNP’s Kirsty Blackman said it was proof that even Tories didn’t like the Tories.

“When even leading Tories are no longer willing to put up with Boris Johnson and his devastating plans for an extreme Brexit – why should Scotland?” she asked.

She added: "Scotland voted overwhelmingly to remain in the EU – but now we face being dragged out against our will, on the hardest terms, by a Tory government we didn’t vote for. It is clear Westminster isn’t working for Scotland and our interests are being completely ignored.

“The SNP will put Scotland’s opposition to Brexit and our right to choose our own future as an independent country at the heart of the coming election. It is clearer than ever that the only way to properly protect Scotland’s interests is to become an independent country.”

Stewart was something of a dark horse during the Tory leadership contest, unexpectedly making it through the first three rounds.

During the contest he was forced to deny that he had served MI6. He also admitted smoking opium in Afghanistan.

A Tory Party spokesperson said: “We would like to thank Rory for his hard work and wish him all the best for the future.”

They said parliamentary candidate for Penrith and The Border would be selected “in due course”.