Ukip has its first-ever elected MP after Douglas Carswell won the by-election he triggered in his Clacton constituency by defecting from the Tories. Here's everything you need to know about the landmark result.

Stunning as well as historic

It was quite simply a resounding victory for Carswell, who won a higher share of the vote (59.7 per cent) standing on a Ukip ticket than he did for the Tories (53) at the last general election - winning with a swing of 44.1 per cent.

As well as becoming Ukip's first elected MP, the Clacton result represented the largest increase in votes by any party in any UK by-election ever.

His win largely came at the expense of Tory votes, although Labour and the Lib Dems both saw their vote down by over ten per cent amid claims the Lib Dems lost their deposit.

In his acceptance speech, the re-elected Carswell, who had become disillusioned with the Tories under David Cameron, said there was "nothing that we cannot achieve".

The Tories weren't the only party having a bad night...

Clacton wasn't the only by-election taking place last night, as Labour held on to Heywood and Middleton in a vote triggered by the death of Kim Dobbin last month.

The vote was so close - just 617 votes in it - that Ukip demanded a partial recount.

Ukip leader Nigel Farage has made much in recent days of wanting to take on Labour in its northern heartlands, and in May Ed Miliband's party was pushed into second place in the European Parliament elections by Ukip.

This chart from Statista shows that Ukip has mainly drawn its support from disenchanted Tory voters, but also the Lib Dems and Labour.

In short, all three main parties at Westminster have reason to be extremely worried by last night's results.

Hold on a second though...

The Independent's Andy McSmith said the result in Clacton-on-Sea, while "extraordinary", may "yet turn out to be one of those interesting events that were not quite as important as they seemed at the time".

He compares Ukip's emergence to the breakaway SDP in 1982 but argues that if the Tories win the next election and deliver a EU referendum, the raison d'etre for Ukip will melt away, in the same way Labour's shift to the centre after Michael Foot did for the SDP.

What have the other parties said?

Tory chairman Grant Shapps admitted on BBC Breakfast that the result in Clacton was a "wake-up call", but could only really reiterate his oft-repeated mantra that a vote for Ukip was ultimately a vote for Miliband and Labour.

Labour meanwhile, through vice-chairman Michael Dugher, said David Cameron had been "humiliated" in Clacton and that Labour would continue to take on Ukip, without directly referencing the closeness of the result in Heywood and Middleton.

What happens now?

On the eve of the Tory Party conference Ukip scored its second major defection when Mark Reckless said he was 'doing a Carswell' and moving to Ukip and triggering a by-election in his own constituency. The vote in Rochester and Strood will take place on November 6, and while the indications are that the result will be much closer than in Clacton, if Reckless wins handsomely, expect to see yet more Tory MPs switching sides, and, in turn, a lot more of this:

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