The 2017 exit poll predicted one of the most surprising electoral outcomes in recent history and was one of the most accurate in four decades.

But be wary. In 2015 the BBC exit poll failed to call the Conservaive majority, predicting Conservatives on 316 seats, 15 seats off the actual total of 331.

The famous 1992 exit poll both ITN and the BBC predicted a hung parliament - but John Major's Conservative Party government had, in fact, held its position.

Because the exit poll is conducted in a small fraction of the 39,000 polling stations in Britain, it is inevitably subject to a margin of error.

Exit polls have been used to predict the results of general elections in the UK for several decades now, with varying levels of accuracy.

Modern exit polls are sampled polling stations in marginal seats, asking how voters exiting polling stations had voted.

Pollsters approach one voter out of a "given number", such as six, eight or 10, based on an estimated national turnout agreed in advance between the polling companies and the broadcasters.

Read more here:

The Conservatives are set to win an overall majority of 86 in the general election, according to an exit poll for the BBC, ITV and Sky News.

The survey taken at UK polling stations suggests the Tories will get 368 MPs - 50 more than at the 2017 election - when all the results have been counted.

Labour would get 191, the Lib Dems 13, the Brexit Party none and the SNP 55.

The Green Party will still have one MP and Plaid Cymru will lose one seat for a total of three, the survey suggests.

The first general election results are due before midnight, with the final total expected to be known by Friday lunchtime.

Image source, PA Media

The polls have closed and counting has begun.

However we don't expect results from any of London's constituencies until after 01:00 BST with some unlikely to be unannounced for a number of hours afterwards.

BBC London

Hello, and welcome to the BBC London's coverage of the general election in the capital.

The city will be returning 73 MPs in total.

Who will they be? You'll be able to find out on our live feed here.

We'll be bringing the latest results as soon as they come in overnight, plus analysis of the results and information about the lead-up to the poll and the counties' constituencies.

Get in touch by email, tweet, external or post on our Facebook page, external with your thoughts - or let us know how you are spending election results night.