I am going to stick my neck out and say it’s going to be Boris by 58 seats. How do I reach that conclusion? Because the pollsters have a problem with estimating the Labour vote. And this time it is their turn to over-estimate it. In 2010 the final polls put Labour on between 27 and 29 per cent – against the 29.7 per cent which Gordon Brown actually achieved. In 2015 the last polls put Ed Miliband between 33 and 35 per cent – compared with the 31.2 per cent he actually achieved. All polls converged on predicting either a dead heat or a Tory lead of 1 per cent – except, that is, for a Survation poll the day before the election which predicted a Tory lead of 6 per cent, remarkably close to the 6.6 per cent lead which gave David Cameron his majority of 15. The only problem was that this poll was not published because the pointy-heads at Survation didn’t believe it – they thought it was a rogue poll.
Their fingers burned by the experience of 2015, polling companies adjusted their methodologies, with the result that in 2017 they horribly under-estimated the Labour vote. Undoubtedly there had been a lot of movement in the Labour vote during the election campaign. But, even so, there was a huge gap between the final published polls – which put Labour on 33-35 per cent of the vote – and the 41 per cent which Jeremy Corbyn achieved, thereby depriving Theresa May of her majority.
By contrast, the pollsters have been relatively good at predicting the Tory share of the vote over the past decade. In 2010, the final polls put them on 35-37 per cent, against the outcome of 36.9 per cent. In 2015 the last polls predicted 34-37 per cent, against the outcome of 37.8 per cent. And in 2017 they gave May 41-46 per cent of the vote, against the 43.5 per cent she actually achieved.
Putting all this together, I suspect the pollsters will have over-corrected their methodology again – this time over-estimating Labour support. I expect Boris to achieve the 43-45 per cent that the final polls have predicted. Corbyn, however, I expect to under-perform the 33-35 per cent that the final polls have given him. Result: a pretty firm victory for Boris.
If I am right I will, of course, be parroting my forecast for years to come. If I am wrong I trust that this blogpost will quietly fall into obscurity. That is, after all, the way that forecasters and psychics establish their reputations: by accentuating that which they get right and forgetting what they get wrong.