The Long March to 10 p.m.: How the U.K. Exit Poll Is Made
In the offices of the U.K. Labour Party, there were astonished cheers. At Conservative headquarters, it was as though the air had been sucked out of the room. The moment the exit poll dropped at 10 p.m. on election day in 2017 was the moment Theresa May realized she had spectacularly failed.
It was the second time in a row the exit poll -- more reliable than normal surveys because it’s based on asking people how they actually voted -- had confounded expert opinion. Two years earlier, it told the nation David Cameron had a chance of winning an overall majority, when everyone expected a knife-edge result.
Sitting in Labour headquarters that night in 2015, Tom Hamilton had been in charge of briefing the politicians who would go on air to respond to the exit poll. “We had three different scripts,” he said. “The one scenario we didn’t have a script for was the Tories getting an overall majority.”
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As soon as he saw the poll that night, he knew in his heart it was right. Nevertheless, he said, he was persuaded to send out a briefing line that Labour was doubtful about the poll’s reliability. “I don’t think we were,” he said. “But there wasn’t very much else to say.”
At that point, the hope the poll might prove to be wrong when the results come in is all a party can cling to. In 2017, Conservatives told each other it had been wrong before. Those with long memories recalled 1992, when two exit polls predicted Tory Prime Minister John Major would lose his majority. Then, as results flowed in overnight, it became clear he had won.
Experiences like 1992 are also burned into the consciousness of Rob Ford, professor of politics at Manchester University, but for a different reason. He’s one of the team of 10 specialists who will put the poll together.
The team will assemble around midday Thursday in a basement at the BBC -- even the location is supposed to be a secret -- where a security guard has instructions to admit no one whose name isn’t on the list.
Lunch will be sandwiches from Pret-A-Manger. Dinner, if they’re lucky, will be pizza. But the treat, for academics who’ve devoted their lives to elections, is they get the first insights into how people have actually voted.
In 2017, Ford said, “we knew that something could be happening from pretty much the first data drop.”
Since dawn, interviewers working for Ipsos-MORI will have been waiting at 144 carefully chosen polling stations around the country. They count the people who have voted, and stop a fixed proportion to ask them which party they backed.
Their reports start to arrive with the number crunchers around lunchtime.
In 2017, a total of 20,000 voters were interviewed. By using historical data from previous elections, the poll aims to measure shifts in voting patterns across the country. Those are then combined to predict the results in different seats.
The team is led by John Curtice, a wild-haired 66-year-old professor of politics from Strathclyde University, who has become a fixture on TV screens as the BBC’s polling guru.
Psephology -- which comes from the Greek for pebbles, which were used for voting in antiquity -- involves science, math and ultimately a judgment call on how to interpret it all. For Curtice, it’s also an art form and a lifelong passion.
Part of the art of the poll is identifying how different parts of the electorate are shifting. This election, like the last one, involved the Tories trying to persuade people who’ve never backed them before to support the prime minister in order to deliver Brexit. Equally, Labour have been trying to hold on to those voters with pledges to tax the rich and end austerity.
If the result is tight, things become especially difficult. Curtice points out that an exit poll putting the Conservatives on 322 seats could be within five seats of two radically different outcomes: If Boris Johnson were in fact to get 327, he’d be leading a majority government and taking the U.K. out of the European Union. If he won 317, he could be on his way out of office.
Three broadcasters -- the BBC, Sky and ITV -- jointly fund the poll, but very few of their staff are allowed to know what it says. Even those in on the secret are told only at the last possible moment. Because they need time to prepare visuals, the first people told are graphics staff, even before senior correspondents.
But in 2017 there was a leak. The BBC’s Andrew Marr called May’s chief of staff, Fiona Hill, to get reaction before the poll was released, according to two books about the campaign. At this election, Marr is on the early morning shift, so won’t get advance sight of the findings.
For the exit-poll team, 10 p.m. is barely halfway through what Curtice describes as “the long march.” Their next data points are the actual results. As these come in, starting at about 11 p.m., they offer solid information on how the vote is shifting, and the model increasingly relies on this as the prediction is refined.
It doesn’t matter that the early declarations in U.K. elections tend to be from Labour-supporting seats in places like Sunderland, in northeast England. Curtice and his team are looking for the change in votes, not just the headline result.
“Once 50 results have come in, that’s what’s driving things,” Ford said. “You’ll see that the projections do change as the results come in. That’s because the model is learning.”
The exit poll has now been right for six elections running. By Friday morning, Curtice will know if his streak has got to seven.
©2019 Bloomberg L.P.