Any Conservative MP pondering whether or not to defect to UKIP may have been planning to wait for the result of the Clacton by-election.  After all, to leave one party for another – let alone a newcomer such as UKIP – is to risk one’s pay, career and pension.  And most Tory MPs are less brave (as well, it must be added, as less foolish) that Douglas Carswell and Mark Reckless.

Such MPs now have reason to hang on for a bit longer.  Rochester and Strood is a more typical Conservative seat than Clacton.  The latter tops the list of UKIP-vulnerable Tory seats published on this site by Robert Ford and Matthew Goodwin, the authors of Revolt on the Right.  The former isn’t even on it.  Any Conservative MP in two minds about defecting may now hang on for a bit longer to see how the second by-election goes.

Reckless’s decision has raised the stakes both for Nigel Farage and David Cameron.  If UKIP wins in Rochester, its long march will gather pace.  But if the Conservatives win, it will be halted in its tracks (at least for the moment).  Cameron will be able to claim that Farage has been seen off.  Any calculating Tory MP may re-calculate.  It’s just possible that Reckless may actually have done Cameron a favour.