David Cameron faces his biggest by-election defeat yet at the hands of Ukip defector Douglas Carswell in Clacton. The first poll of the constituency, which handed ex-Tory MP Carswell 53% of the vote in 2010, predicted he would be returned as Ukip's first elected candidate in Westminster with eye-watering support of 64%. The Conservatives are trailing an enormous 44% behind on 20%, with Labour on 13%. Survation's poll for the Mail on Sunday newspaper is a disaster for the Tories, who had made clear they planned to fight the seat vigorously following Carswell's shock defection on Thursday.