Are the betting markets more accurate guides to election results than pollsters? In this instance, yes they were.
The Ladbrokes figure is based on our last percentage lines for each party, which you could have bet at either 5/6 over or under. The pollsters are their respective last published poll and the figures are just for Lab, Con, LD & UKIP. The higher the bar, the more inaccurate they were.
To be fair to pollsters, some of the final polls were a few days before the vote. Also, I’m sure had you actually asked a pollster for a “prediction” they would mostly have got closer as they would have been able to factor in some of the vote going to all of the un-prompted itty-bitty parties on the ballot (Pirates, Christians, Lib Dems, etc.).
I was particularly pleased that our line on An Independence From Europe’s vote share got so close. We had it at 1.5%, they got 1.49%. The only party who actually out-performed the betting market prediction were the Tories.