We went through 3 and a half decades' worth of polls: Here's what we learned

We went through 3 and a half decades' worth of polls: Here's what we learned

Earlier this week, we took the time to have a look at Ipsos MORI’s full history of voting intention polls.  And though there are some methodological changes – starting to weight by likelihood to vote, for instance – it’s fantastic to be able to see data sets going all the way back to 1978.  In the graph below, all we’ve done is collected the data together, ironed out a few bits and pieces, and presented it in the conventional way. 

Here it is:

The graph itself should be self-explanatory: Labour’s figures are shown by the thin red line, with the Tories represented by the – ahem – thin blue line. Background colours relate to which party is in power, and the vertical lines denote general elections.

It’s becoming quite common now to compare poll ratings between parties and politicians only over a course of a few weeks or months or so; as a result, it’s so rare to see an unbroken line of data points stretching back so far. 

With this long-lens picture, here are some interesting things to take away from this graph:

1.  No governing party has been ahead by double digits at this point in the Parliament and gone on to lose the next election.  Though, admittedly, there are only two precedents for this: by October 1998 and November 2002, Labour were ahead by 27 points and 12 points, respectively.  What’s more, this is not to say that a governing party can’t win with only a small lead – or no lead – by this point: Thatcher’s Conservatives were 9 points behind Labour in October 1980 and went on to win in a landslide in 1983.  Either way, the 18-point lead the Conservatives have at the moment would suggest – if recent history is anything to go by – that Theresa May has reason to be optimistic of her chances at the next election.

2.  The Falkland’s victory wasn’t Thatcher’s only saviour.  In the early days of her premiership, the Conservatives were being beaten in the polls consistently by the Callaghan-led Labour opposition; and even after her party’s meteoric rise in the polls following the Falklands, she would have had some difficulty in the upcoming election if faced with a Labour party with the kind of polling numbers it had earlier in the Parliament. What made her victory secure was the plummet in the Labour vote which took place almost immediately after Michael Foot took over the Labour leadership in November 1980.

3.  The speed with which the parties diverged after the 1992 election is extraordinary.  Although it has been well-documented, it’s still remarkable to see how quickly the Conservative support plummeted after Black Wednesday of September 1992 and how strongly Labour capitalised on their opponents’ grief.  By 1994, the Labour lead was stronger than anything even Thatcher had managed to overcome.

4.  For the first three years of the first New Labour government, the polls hardly shifted at all.  Unlike Thatcher, whose party experienced a troubling time in the polls almost immediately after coming to power, Tony Blair’s governing party had little trouble at all.  What’s more, not only did Labour’s support remain steady – the Conservatives failed to get any serious rise in their polling number until about 2000.

5.  But while New Labour proved themselves masters at getting votes, they also knew how to shed them.  Between the elections in 1997 and 2010, the party lost almost exactly 33% of its share of the popular vote.  And with the Conservatives losing 28.5% of their share of the vote between 1979 and 1997, Labour managed to lose proportionately more of their share of the vote than the Tories – and in a shorter time period, too.

6.  Brown’s lead in the polls was short-lived, and may not have survived a campaign, either.  But, according to these MORI data points, his lead was clear and quite sizeable – by the end of September, Labour were 13 points ahead of the Conservatives.  As to what would have happened if Brown had decided to go to the country, we simply can’t know – but there are decent points to be made on both sides of the debate.

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ICM's Polling Bombshell

ICM's Polling Bombshell