This morning’s ComRes poll in Rochester and Strood has UKIP defector Mark Reckless 13 points ahead of the Tories in the constituency. Conservative HQ had pretty much openly priced in defeat in Clacton two weeks ago, but losing again on November 20th would be a disaster for them. David Cameron visited the seat last week and plans to make four more trips ahead of the vote.

Imagine the mutinous mood in the Tory party if, even after such a high-profile effort, they still went on to lose.

UKIP are buoyant at the moment and are confident they can pull off a win which just a few days ago would have been considered highly unlikely. It is worth learning the lesson of another recent by-election: Labour’s win over UKIP in Heywood and Middleton by just 600 votes.

One senior UKIP source tells me they would have won the seat if the party had diverted resources from Clacton – which was in the bag – up north. However, I’m told UKIP HQ insisted on putting everything they had behind Douglas Carswell because “we owed him” for defecting. Understandable, yet notable nonetheless that privately the party is kicking itself for not doing everything it could in Heywood.

UKIP will not make the same mistake in Rochester and Strood. The party’s policy of guaranteeing defectors undivided attention (presumably part of the package convincing them to jump ship) means Reckless will receive the same firepower as Carswell. It is looking like it will be increasingly difficult for the Tories to hold on to this key seat in a month’s time.