In the space of one hour, Britain has a new PM

Theresa May, the next Prime Minister, greeted by Tory MPs outside St Stephen's Gate, Westminster

The Prime Minister has changed, just like that.

At 11.30am  this morning the Westminster journalists, those of them who were not in Birmingham for Theresa May’s leadership speech, were trooping  along the Thames Embankment towards  the venue for Angela Eagle’s planned challenge to Jeremy Corbyn.

Then the balloon went up that Andrea Leadsom, after a bruising weekend of headlines, was unexpectedly announcing that she was withdrawing from the Tory leadership race.

An about-turn that wouldn’t have shamed the Trooping of the Colour was executed.

By 12:30am we had rushed from Leadsom’s campaign headquarters to the St Stephen’s entrance of the Houses of Parliament to hear Graham Brady, the chairman of the Conservative 1922 committee, formally declare that Theresa May is the new leader of the party. She is, de facto, the Prime Minister of the United Kingdom.

Right now Theresa May is on a train back from Birmingham, David Cameron is at the Farnborough Airshow, and the Queen who would appoint a new Prime Minister is in Balmoral.

It has been a stunning hour in an incredible few weeks of British politics. We knew the fall-out from Brexit was going to be profound and dramatic but this is  a swift and ruthless unravelling of the thread.

It has claimed several careers already - David Cameron, Michael Gove, Boris Johnson amongst them - split the Labour party from it’s leader and heightened expectations for a second Scottish referendum.

There will be a new Cabinet in weeks. I thought it highly symbolic that George Osborne allowed himself to be photographed, looking relaxed and comfortable, with his children at Silverstone this weekend. He could be on the way out. 

There could be a general election in months, the pressure will certainly be on, and that will be good news for one man at least - Jeremy Corbyn.

For the far-left losing troublesome Labour MPs to Brexit-supporting constituencies would a year-zero win, allowing them to put Corbyn-friendly candidates in place next time. Losing can be blamed on the rebel MPs, so do not prepare for a Labour revival.

For the SNP in Scotland it should be relatively unaffected by an election and has the finances and organisation to be ready in no time. For the SNP an election would be a simple platform to argue against Scotland being taken out of the European Union.

Prepare for a new Prime Minister is all we can say for certainty.

Brexit has shaken Britain to the core, the centre has fallen apart.