Exactly one month ago, the Ladbrokes betting suggested the race to be the biggest party after the election was an exact coin toss, with both the Tories and Labour quoted at 10/11. Now, the Tories are pretty strong favourites; the odds imply there is a 58% chance they will come out with most seats.
What’s changed? Well, not the polls; the averages have been very consistent for about five months now. It’s very close, although Labour leads continue to be more common. Here is the tracker provided by the excellent May2015 site.
The political science models have moved towards Labour in recent weeks. That’s because they build in an expectation that the polls will drift towards the Conservatives in the weeks leading up to election day. That doesn’t seem to be happening yet, and the clock is ticking down, hence Labour’s slim advantage has more chance of holding. The Tories probably need to have around a 2% national vote share lead on polling day to win most seats.
Given all of that, the moves in the betting markets don’t seem to make a lot of sense. I think it’s a result of more and more people actually starting to think about the election the nearer we get, and a very large number of those people believing that Ed Miliband is too much of an electoral liability to become PM, irrespective of what the polls say.