The first big moment of drama tonight comes in just over half an hour, when the exit poll is announced.

It's a major endeavor paid for by the UK's three main broadcasters -- the BBC, ITV and Sky -- which asks voters to repeat their vote, in secret, after leaving their local polling station.

It's usually accurate. The exit poll predicted the winning parties’ seats totally exactly right in both 2005 and 2010, it was 14 seats off in 2015, and just three off in 2017.

The poll also usually provides a shock that pundits and regular opinion polls hadn’t seen coming. That was the case in both 2015 and 2017, when the exit poll stunned politicians and voters alike by predicting a comfortable Tory win and a hung Parliament respectively.

Its findings are kept tightly guarded until 10 p.m. when polls close.

The poll's accuracy is exactly the reason for its secrecy. Having live data on how an election is going is sensitive for all sorts of reasons: it could be used to make money, it could be used to interfere with the democratic process. That's why the location and identity of the political scientists working on it is kept secret.