Exit poll: How does the UK's unique election litmus test work?

Minutes after the UK polls close late Thursday evening, Brits will have a good idea of who their next prime minister will be.

The exit poll announcement usually takes place at 10pm, with many so confident about the poll's prediction they'll resume normal programming.

The system has been in place for decades, but a new method means that Brits can go to bed on Thursday night being fairly sure of which government they'll awake to the following morning.

The New Arab takes a look at the UK's unique polling system.

What is an exit poll?

An exit poll is a polling system that takes a bite size sample of voting intentions to get an idea of what the election results will be before all the votes are counted.

The UK's exit poll is announced at 10pm, although its architects know the results much earlier but can't reveal them until everyone has cast their vote, so as to not influence the election.

Funded by the BBC, Sky News and ITV, it is carried out by pollsters Ipsos and analysed by a team of experts at a "secret bunker" in central London.

How does it work?

From these results, experts will be able to determine the percentage of votes for each party and how many seats they will gain, with a party needing 326 to command a majority.

Opinion polls involve face-to-face or telephonic questions about who they intend to vote for in a coming election.

The UK's exit poll sees fieldworkers take a sample from a number of voters leaving 130 selected polling stations, with the numbers added up and analysed.

Those selected at random for the poll will fill out a mock election slip and then cast their ballot anonymously to give a more accurate indication of voting intentions.

How accurate is it?

Before this new system of anonymous voting was unveiled, exit polls were far less accurate.

In the 1992 election, two separate polling companies predicted a hung parliament; Prime Minister John Major's Conservative Party went on to win 332 seats, commanding a majority.

Recent elections have been considerably more accurate. In the last election, the exit poll predicted the Conservatives would win 368 seats - they got 365 - with Labour expected to take 191 - they got 203.

In 2017, the Conservatives were on 314 in the exit poll and got 318, while Labour were predicted to get 266 but got 262.

How is the UK exit poll 'unique'?

Many countries have exit polls, but the UK's has become known as one of the most accurate polling thanks largely to changes conducted in the 2000s when broadcasters decided to work together using one survey company.

The fieldworkers go to the same polling stations and compare previous voting patterns, along with other data, to come up with a prediction much closer to the actual results.

The UK's unique 'first past the post' parliamentary system also means this is considered when calculating the seats for each party.