In the last few weeks we've had two by-elections, as a consequence of which we now have the first two UKIP MPs. And in both cases the media have described these as Tory losses and UKIP gains, showing a massive swing to UKIP and the start of a massive shake-up of British politics.
There's just one problem with this narritive: in both cases the winner of the election was the person who was the MP beforehand. What's more, both Carswell and Reckless were, by all accounts, both good and popular local MPs.
So, what we have is not necessarily a big swing towards UKIP as an outworking of the known phenomenon that the incumbent always has a big advantage in an election - it's much easier to remain elected than to become elected. (Which is not to say there isn't some sort of a swing going on. Of course there is. But it's certainly not of the size that may be being presented and may not even be in the direction that's being presented.)
The reason this is important is that we have a General Election coming up. If the by-election results show a massive swing from the Tories to UKIP then that means UKIP can expect to win many seats, where if the results show a much more modest swing then it means UKIP can expect to win only a few seats.
And, yes, based on the results from last night I'm now much more confident of my prediction that UKIP will get between 0 and 5 seats at the General Election. Specifically, they will probably hold Carswell's seat, might hold Reckless' seat, and may possibly gain 1-2 more seats due to defections (and then hold them). And Nigel Farage will probably win a seat, provided he chooses it very carefully.
But I doubt they'll get much beyond that. The First Past the Post system just favours the two big parties to too great an extent.