Seven months to go, historical polls still point to a narrow Tory election lead, with Labour the largest party

Seven months until the General Election it’s time for an update of my chart of what historical polls and votes can tell us about the election ahead.

The earlier posts are available here, including discussions of the methodology. As ever, I’m using Mark Pack’s brilliant spreadsheet of historical polls.

The new analysis suggests that:

Opposition lead at the election =

(0.6 x Opposition lead seven months before the election) – 4.3pts

According to UK Polling Report, Labour’s current lead is 4pts. This means the analysis suggests a Tory lead after the election of just under 2pts: probably not enough for a majority, and with Labour the largest party.

This is almost exactly the same prediction as from polls a year before elections. It is also similar to – though marginally better for the Tories than – the prediction from polls two years before elections.

But now focus on the elections in the area in the red box below: where the polls were narrow at this stage. In these cases there is a huge amount of variation in the results: from a healthy Opposition victory (’79) to a comfortable Government majority (’87).

So from where we are now, previous elections suggest either main party could build a majority-sized lead.

That said, the fact the polls have followed the historical trend for at least the last 17 months provides some evidence to support the model’s prediction of a very small Tory lead.

Health warnings

There are lots of reasons this analysis isn’t perfect and is best read in combination with others. I went over a few of them last time.

The continued strength of Ukip is a particular weakness: whether they fade in the months ahead, or whether they don’t, this run-in to the election will be unusual, so precedent may be less helpful.

  1. This is utterly pointless because it leaves UKIP out of the equation. You cannot lump UKIP in with the “opposition” as the Lib Dems were last time because the Lib Dems were (though not since they joined the coalition) a progressive party and thus could be lumped in with Labour as the opposition. Besides, they had far less grass roots support than UKIP now does, everything has changed since the last election. When Cameron says that “if you go to bed with Farage you will wake up with Milliband” he isn’t far wrong.

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