Jeremy Corbyn wins

Jeremy Corbyn has, as expected, won the Labour leadership election. I say as expected but the reality is we didn't actually have that much evidence to go on during the campaign - noise on Twitter and size of crowds at campaign meetings are bunk, the reports of what the campaigns canvassing operations found were very erratic and while we had concrete figures for local party nominations we didn't know how good a guide that would be to how local members actually voted. The expectation that Jeremy Corbyn was going to win was based upon the polls, or more specifically, two YouGov polls, both conducted for the Times.

We only have to go back a few months to another election when there was a wide expectation of a particular result, based on what the polling evidence was telling us and it didn't work out so well. Polling an internal party election is a very different challenge to polling a general election, in many ways a more difficult one - you have to track down respondents from a very small pool. The huge influx of new members and registered supporters made this election particularly tricky - YouGov had more demographic data about Labour party members than they did when they polled the 2010 leadership election, but that was only about half the electorate. The rest were an unknown quantity. Rationally I was confident in the polling showing Corbyn was ahead, not least because it showed Corbyn winning amongst every demographic group, but that didn't stop the nagging fear that come Saturday Jeremy Corbyn would have trailled in last place and the whole of the media would have been following the wrong story based on wrong polls.

In the event, the YouGov poll actually seems to have matched up well against the final result, though there was a month between fieldwork and the end of the contest. The last poll was conducted back in August, and had figures of Corbyn 53%, Burnham 21%, Cooper 18%, Kendall 8%. This was before registration to take place in the election closed and a couple of days later when Labour released the final figures for the number of members, supporters and affiliates YouGov reweighted the figures to reflect the proper balance of the electorate. That took Corbyn's share up to 57%. In the event Corbyn won with 59.5%

With the contest over, now we wait to see what the impact will be. I wrote at greater length here about what the polls could tell us about how well or badly Jeremy Corbyn will do (long and the short of it, as far as direct evidence is concerned they can't tell us much). Personally I wouldn't expect some immediate crisis in Labour support unless the party completely rips itself apart (most people simply don't pay enough attention to what the opposition party is up to!), there could even be a short term boost from a new leader. We shall see.