[DTV]

In terms of the exit poll, the team who model it based on the 'second' secret ballot data collected by Ipsos (it isn't actually the results of a poll that are broadcast) are located at the BBC under John Curtice and are kept under guard in a windowless room without access to their mobile phones. The only communication they have with the outside world is the data coming in and food deliveries, while being escorted when they need the toilet. Typically, they know the basic result by midday, but only begin to finalise the story and headline* from the early-evening. Representatives of the broadcasters are briefed in person (at the BBC) as late as possible during the 21:00 hour, though the seat tally is not finalised until fairly late. Graphic producers are among first to be told, but some senior correspondents definitely know in advance - Andrew Marr is known to have asked the May team for a response in 2017 slightly before 22:00.

*The headline - e.g., 'Labour landslide', 'Hung parliament', 'Conservative majority' or 'Conservatives largest party' - is decided by the exit poll team based on specific guidelines. For instance, in 2015 and 2017 'Conservatives largest party' was chosen rather than 'hung parliament' as a Conservative majority was a possibility within the error margins.