Douglas Carswell has joined UKIP. About bloody time; this is a long awaited move. Carswell has been in closer political alignment to UKIP than to the Conservatives for years; on Europe, on climate change, on localism, on restoring public faith in politics… and his assurances that a move to UKIP was not imminent were noticeable by their absence long before this week.

Following the Conservatives’ dismal performance in May’s European elections, Carswell called for a pact between the Tories and UKIP. Echoing the sentiments of many a disgruntled-Tory-turned-UKIP-voter, he wrote:

A successful business doesn’t blame customers when they walk away. An astute entrepreneur will ask instead what caused the punter to leave, and ask what they need to change to get them back. Those in the business of political retain ought to do likewise…. Attacking UKIP – and by extension those who voted for them – makes no sense.

Unlike his former leader, Mr Carswell understands that the Conservatives do not own by right the votes of the Right. If abused or ignored, those of us who once bled blue can and will find a party that better represents us, much as he has done today. It is this realism and willingness to listen, in the place of the arrogance exhibited by Cameron and his ilk that made Carswell such a popular backbencher.

Discussion has naturally exploded around what this means for both UKIP and the Conservatives. It is, of course, a huge coup for UKIP. The party has a brilliant headline after a recent period of quiet and the possibility of a new MP with a genuine mandate.

More importantly, they have Douglas Carswell, who is no mere backbencher; his is an unquestionable reputation as a respected, interesting and consistent radical who has stuck to his principles by putting himself to the public vote.

What is more, Carswell’s defection to UKIP was done with such grace; he calmly praised the character of the prime minister while stating his reasons with similar dignity, a grace I cannot claim to have possessed those few years ago. Not only has Cameron suffered the kick in the teeth of losing an MP to his greatest foe, but he lost this MP; a bastion of the right of his own party, a great man who is serious about the sort of change that your average grassroots Tory activist deeply wants themselves. And gosh! What a beautiful speech.

One can only wonder what prompted this decision; what straw broke the back of this consistently brilliant backbencher – a maverick, but not prone to froth – and prompted the about-turn from advocating an electoral pact to detonating a nuclear warhead right into the heart of the Right.

This by-election is set to be bitter and both sides will suffer blows. Cameron’s will be more obvious, perhaps, but this campaign signifies a monumental risk for UKIP too. The potent combination of a 12,068 majority and a “thriving” local association, not to mention the sheer rage flooding the veins of the supposed hordes of Tories heading to Clacton, will be quite a force to be reckoned with even for such a popular Member of Parliament. Losing the Clacton by-election would be as disastrous to UKIP’s progress as Farage losing South Thanet at next year’s General Election. Personally, I can’t call it. A poll published today suggests the odds tip in UKIP’s favour but, really, who knows?

The liberal wing of UKIP has real cause to rejoice today; Douglas Carswell will be a lot harder to ignore than members of Young Independence. Following today’s announcement, for the first time in a year I will be dusting off my UKIP rosette, parting ways with thirty pounds and embracing genuine hope for my party’s future.

The next question, if UKIP take Clacton, is who will be next. Will Dan Hannan follow suit? The two have collaborated with great success before; they are both staunch Eurosceptics committed to a localist agenda, a smaller state and personal freedoms – all things about which Cameron gives not a fig. Sadly Jacob Rees-Mogg MP has ruled out a move. But then, again, who can tell? The only things we can say for sure are that today was a brilliant day for UKIP, the liberal wing in particular, and that this is going to be a hell of a by-election.