History, though, tells us that by-elections, however dramatic, usually have little lasting significance. Could this one be different? Here are four ways in which it might.
1. By having an MP at Westminster, Ukip will command greater media attention in the run-up to next year’s election. A Carswell by-election victory will badly dent one of the arguments for marginalising Ukip—however well they do in European elections, they have never won a seat in the House of Commons.
2. Ukip will be able to see off the charge that it is a one-man band. The party has been trying to secure attention for other leading members such as Diane James, its candidate in last year’s Eastleigh by-election. It has had limited success: when journalists want to talk to Ukip, they want Nigel Farage. From now on, they will also have Carswell.
3. In local and European elections, Ukip has done best in seats along the East coast, from the Humber to Kent. Victory in Clacton will increase Ukip’s credibility in other seats, such as Grimsby, Great Yarmouth, Thurrock and Thanet South. Until Carswell’s defection, I still thought Ukip’s vote would be squeezed in next year’s general election, and it would struggle even in these seats. Now I would not bet much money against Ukip winning all of them.
4. Perhaps the biggest impact that Ukip could have on British politics is not in its target seats but in tightly fought Conservative-Labour marginals. Increased media attention and credibility could help Ukip hold on to more votes; and by far the greatest penalty for any Ukip boost would be paid by the Conservatives. Suppose the nationwide “Carswell effect” is worth an extra 1,000 votes to Ukip in each Tory marginal; and suppose these extra supporters deprive the Tories of 600 votes and Labour and the Liberal Democrats 200 each. The net result would be to hand Labour an extra ten seats currently held by the Conservatives.
In a close election, the combination of Ukip’s East coast gains and extra Tory losses to Labour, could decide whether Labour or the Conservatives end up as the largest party. In other words, Carswell’s almost certain by-election triumph could trigger a chain of events which leads to Ed Miliband becoming Prime Minister—and killing off any prospect of the thing Carswell says he wants most of all: a referendum on Britain’s membership of the European Union.
