General Election turnout: Young people finally did what they said they would ... and voted

Opinion pollsters were facing fresh questions today after widespread predictions of a comfortable Tory majority were confounded by the shock election result.

Almost all the final polls published in the run-up to voting put the Tories in line for a clear victory, with leads ranging up to the 13 per cent gap expected by BMG and the 11 per cent gap by ICM. Other polling firms that put the Tories well ahead included ComRes, which predicted a 44 to 34 per cent victory for Theresa May’s party over Labour; ORB, which gave the Conservatives a nine-point margin; and Ipsos MORI, which predicted an eight per cent Tory lead.

Only Survation, which put the Tories on 41 per cent and Labour on 40, was close to predicting the actual result. YouGov had also earlier predicted a hung Parliament in a poll in May based on constituency by constituency estimates — widely dismissed as a rogue result at the time — but put the national Tory lead at seven per cent in its final poll published earlier this week.

The failure of the pollsters to predict the result follows similar mistaken findings ahead of last year’s EU referendum and the 2015 general election. Fraser Nelson, the editor of the Spectator, described the outcome as “another polling disaster” in a tweet containing a graph showing all the final opinion polls before voting.

Experts said a key reason for the inaccuracy of the polls was that the turnout of young voters, who are thought to have backed Labour in greater numbers than older age groups, was higher than expected.

That meant that the “weighting” on voter turnout used to balance the raw poll findings was wrong in most polls and understated the number of Labour voters. Ben Page, from Ipsos MORI, tweeted: “One guess is that after overclaiming their turnout in 2015, this time young have done what they said they would — political weather changed.”

Other factors behind the failed predictions include the significant regional variations in voting, with the Tories performing well in Scotland and seats such as Mansfield in the east Midlands, but Labour surging dramatically in London and performing better than originally expected in Wales.

Pollsters also pointed out that the hung Parliament was the result of the election turning into an overwhelmingly two-party contest, with the Lib Dems and other smaller parties being squeezed.

This meant that although the Tories had their best percentage score for decades and rose six per cent on 2015 key marginal constituencies went against them.

The pollsters were more accurate in London, however. A YouGov poll for the Evening Standard last week correctly forecast a surge in Labour votes and seat gains for the party in the capital.@martinbentham