UK General Election exit polls: What they are, how they work, and their accuracy explained

Keir Starmer is likely to become the next Prime Minister and Labour is predicted to win a landslide, the BBC’s exit poll has predicted.

It has found the Tories will be left with just 130 seats, with the Lib Dems forecast to win 61 seats and Reform UK 13. This is predicted before the ballots are counted.

Exit polls are surveys conducted at polling stations immediately after voters have cast their ballots. At around 144 polling stations across the UK, tens of thousands of voters are asked to fill in a replica ballot paper in private to indicate how they voted. This process provides an early snapshot of the election results before the official count is completed.

Polling company Ipsos Mori typically conducts exit polls at the same polling stations in every election. These stations are selected to be demographically representative of the country, including both rural and urban areas, and slightly weighted towards marginal constituencies. Polling expert Sir John Curtice notes that this method involves comparing current results with those from previous exit polls at the same locations.

To maintain voter confidentiality, a replica ballot box is used. Voters are more likely to participate when they can fill out the ballot anonymously rather than telling an interviewer directly. This method aims to reduce the refusal rate, which is a common issue in polling. The number of people approached at each polling station varies based on the registered electorate of that area, creating a "systematic sample."

Are exit polls accurate?

The accuracy of exit polls has improved significantly over time. For instance, the first British exit poll in 1974 predicted a much larger Labour majority than the actual result. However, recent exit polls have been remarkably accurate. In the 2019 general election, the exit poll predicted an 86-seat Conservative majority, closely matching the actual 80-seat victory margin. Sir John Curtice explains that while exit polls are not perfectly accurate, they have often been more reliable than pre-election opinion polls, particularly in the 2015 and 2017 elections.

What did exit polls predict in recent elections?

• 2015: The exit poll was more accurate than opinion polls but did not predict a Conservative majority.
• 2017: Correctly predicted the Conservatives as the largest party but did not forecast a hung Parliament.
• 2019: Predicted a Conservative majority of 86 seats, very close to the actual 80-seat majority.

What did the 2024 exit poll predict?

Labour is on course for a landslide, according to the exit poll projection, with 410 seats. The Conservatives are set for 131 seats. The exit poll also forecasts the Liberal Democrats on 61 seats, Reform UK on 13 and The Green Party on two.

In Scotland, the SNP are expected to secure 10 seats with Plaid Cymru in Wales on four. It would be the lowest number Tory MPs on record.