Boris Johnson will not have to wait long to decide whether he will taste champagne or bitter tears on election night with a host of key seats determined early on.
Ten Leave-supporting Labour marginals are among the constituencies expected to declare their results in the early hours of Friday, after polls close at 10pm.
Many have been Labour for generations and whether they stay in the hands of Jeremy Corbyn or switch allegiance to the Tories could make all the difference to the timing and manner of Brexit.
One of the earliest is the bellweather seat of Workington in Cumbria. Home of Workington Man, the archetypal voter at this election is is due to declare at 1am.
Labour is defending a majority of almost 4,000 and the most recent poll suggests they could hold it, despite a 60 per cent Leave vote.
So a swing to the Tories here could spell the start of an uncomfortable night for Jeremy Corbyn.
Nine other key seats across the North and Midlands are expected to be among those declared by 3am. All share three things: they are voted Leave in 2016 and have a Labour MP.
Boris Johnson (pictured today in Wales) will gain early signs of how his campaign to be returned to Downing Street is going with a host of key seats determined in the dead of night
Labour is defending a majority of almost 4,000 in Workington and the most recent poll suggests they could hold it, so a swing to the Tories here could spell the start of an uncomfortable night for Jeremy Corbyn (pictured today in Glasgow)
Darlington in County Durham is due to be next up around 1.30am, followed by Wrexham in north Wales and Stockton South, both of which voted 58 per cent in favour of Leave, at 2am along with Burnley (66 per cent Leave).
The other five are due around 3am: Great Grimsby (71 per cent Leave), Peterborough (63 per cent), Blackpool South (68 per cent), Newcastle-under-Lyme (62 per cent) and Bishop Aukland (60 per cent).
Mr Johnson is on course to win the general election with a majority of 28 that would allow him to complete Brexit, according to the YouGov polling analysis which correctly predicted a hung parliament in 2017.
But that majority is down from 68 seats a fortnight ago and the analysis also shows some of his top ministers, including Foreign Secretary Dominic Raab, could lose their seats.
YouGov’s final MRP model predicts that the Conservatives will win 339 seats, with Jeremy Corbyn’s party on 231 and the Liberal Democrats on 15.
YouGov warned that the margin of error could put the Tory seat total as low as 311, which would mean another hung parliament.
The Conservatives are predicted to gain 22 seats, including in Labour heartlands such as Ashfield, Bassetlaw and Tony Blair’s former seat of Sedgefield.
However, there are signs that Labour is ‘patching the cracks’ in its so-called ‘red wall’ of seats across the North and the Midlands.
Conservative strategists fear that an ugly row over the NHS on Monday has damaged their campaign and candidates say the election is now ‘on a knife edge’.
The Tories’ shrinking lead means that Labour are now on course to retain Tory target seats such as Tom Watson’s former constituency of West Bromwich East.
The impact of Brexit Party leader Nigel Farage’s decision to only run in Labour-held seats will also be revealed.
Here is how election night is shaping to pan out:
10pm
Polling stations close, followed immediately by the publication of the exit poll. It will be announced live on the BBC, ITV and Sky News, and will offer the first clues as to how the night will unfold. At each of the past few elections, the exit poll has produced a very accurate projection of the actual result.
By 11pm
Two constituencies are racing to be first to declare: Houghton and Sunderland South and Newcastle-upon-Tyne Central.
Both results are expected around 11pm and both are safe Labour seats, so it will be the change in Labour’s share of the vote – and the size of a potential swing to the Conservatives – that will be most useful in providing further clues to the overall election result.
There should also be the first indications of turnout.
By 12am
Four more safe Labour seats are likely to have declared, all in north-east England.
Again, look out for any evidence of a change in Labour’s vote share and a possible swing to the Conservatives.
By 1am
Nigel Farage took his Brexit party campaign to Workington, but will he steal votes off Labour and hand it to the Tories, or visa versa?
Workington could be the first seat of the night to change hands.
If the Conservatives take it from Labour, Boris Johnson might be on course for a comfortable majority in the new parliament.
If Labour holds on, the overall result could be a lot closer.
North Down should be the first result of the night from Northern Ireland – a seat formerly held by the Independent MP Sylvia Hermon, and being targeted at this election by the DUP, the Ulster Unionists and the Alliance.
By 2am
Results will start to pick up. If Labour is doing well, they may take Carlisle, Putney, Thurrock and Vale of Glamorgan from the Conservatives.
If Labour is doing badly, they could see the likes of Stockton South, Wrexham and West Bromwich West being gained by the Tories.
Plaid Cymru will hope to hold Arfon and Dwyfor Meirionnydd, while the DUP will be looking to keep Lagan Valley, Londonderry East and Strangford.
The first results will come from Scottish seats being defended by the SNP, such as Dunbartonshire West, and Lanark and Hamilton East.
By 3am
Labour might defeat Iain Duncan Smith (left) in Chingford and Woodford Green, while the Lib Dems could take Esher and Walton from Dominic Raab (right)
A flood of results is expected. Former Tory MP Dominic Grieve is hoping to win Beaconsfield as an Independent.
The Lib Dems will want to hold Brecon and Radnorshire, which they gained from the Conservatives earlier in the year, and retake Nick Clegg’s former seat of Sheffield Hallam from Labour.
Labour might defeat Iain Duncan Smith in Chingford and Woodford Green, while the Lib Dems could take Esher and Walton from Dominic Raab.
The result is due from Dartford, a bellwether seat since 1964.
The SNP have their eyes on the Tory seats of Ochil and Perthshire South and Stirling. If Labour is having a good night, they will be making gains in places like Telford and Worcester.
If the Tories are performing well, they will hope to take seats like Great Grimsby (a Labour seat since 1945), Bishop Auckland (Labour seat since 1935) and Don Valley (Labour since 1922).
Jeremy Corbyn’s result in Islington North is due, as is Jo Swinson’s result in Dunbartonshire East. Sinn Fein will be hoping to keep their marginal seat Foyle.
By 4am
Over half of the results will be in, and the overall trend of the night should be clear.
Labour targets such as Harrow East, Loughborough and Milton Keynes South will declare, likewise Lib Dem targets like St Albans and Cheltenham. All are being defended by the Conservatives.
Labour will hope to hold the ultra-marginal seats of Canterbury and Crewe and Nantwich, as well as Ipswich, Lincoln and Rother Valley, which are all Tory targets.
Plaid Cymru is defending Ceredigion against challenges from the Lib Dems, Labour and the Tories.
The SNP will hope to hold Fife North East and with a larger margin than they managed in 2017, when they had a majority of just two.
The Ulster Unionists are hoping to take Fermanagh and South Tyrone from Sinn Fein.
By 5am
By 5am Boris Johnson should know whether he’s safely back in Uxbridge and South Ruislip, where he won only a slim majority over Labour in 2017
Anna Soubry should have discovered whether she’s been able to hold Broxtowe for the Change party.
Boris Johnson should also know whether he’s safely back in Uxbridge and South Ruislip, where he won only a slim majority over Labour in 2017.
Kensington, another of Labour’s ultra-marginals, should have declared by now, although the result in 2017 needed several recounts and wasn’t confirmed until nearly 24 hours after polls closed.
The Lib Dems have a chance to make a couple of gains from the Tories in Cheadle and Hazel Grove, while the SNP could do likewise in Gordon.
Dennis Skinner could be unseated by the Conservatives in Bolsover, and other Labour seats at risk include Ashfield, Colne Valley and Keighley.
By 6am
Result should have slowed to a trickle.
A handful of seats in London could deliver some late upsets: Labour is hoping to take Chipping Barnet and Hendon from the Conservatives, while the Liberal Democrats could unseat the Tories in Finchley and Golders Green and Richmond Park.
The Lib Dems are also eyeing the Tory seat of Wells.
By 7am
Remainer Caroline Lucas will have discovered if she has been re-elected as the Green MP for Brighton Pavilion.
By 10am
There is the possibility of some very late gains for the Lib Dems in South West England, who are hoping to defeat the Tories in Cornwall North, St Austell and Newquay and St Ives.
Recounts could delay some of the declarations from earlier, but every seat is due to begin counting overnight so there is a good chance all 650 results will be in by mid-morning.
How will the broadcasters cover it?
BBC coverage will be led by major event lynchpin Huw Edwards. He will be joined by Reeta Chakrabarti, Andrew Neil, Tina Daheley, while Jeremy Vine will take his place at the swingometer.
The 2019 election programme team will also include political editor Laura Kuenssberg, Europe editor Katya Adler, economics editor Faisal Islam, and media editor Amol Rajan, alongside polling expert Professor Sir John Curtice.
Across the country the broadcaster will also have BBC Breakfast’s Naga Munchetty, Andrew Marr, Martha Kearney, Nick Robinson and Lucy Manning, plus Sarah Smith and Kirsty Wark broadcasting live from Scotland.
Sophie Raworth will analyse the results as they come in on a giant constituency map of the UK.
Sky pulled the upset of the election broadcast operation when it announced that former Speaker John Bercow would form part of its team.
He only stepped down from the role at the end of October, shortly before the election was called. But he is seeking to create a career as a pundit.
He will join veteran anchor Dermot Murnaghan, with added input from political editor Beth Rigby, deputy political editor Sam Coates and economics editor Ed Conway.
Channel 4 is hosting a live eight-hour Alternative Election Night.
Coverage will be hosted by its veteran presenter Krishnan Guru-Murthy and comedian Katherine Ryan along with reality television star and radio DJ Rylan Clark-Neal, who will be ‘sense-checking results with a specially invited studio audience’.
Clare Balding will have the results as they happen, political comic Matt Forde will run an ‘alternative news desk’ and Judge Rinder will be out and about at votes.
The broadcaster said they would be joined by ‘an eclectic mix of the country’s biggest political figures’, including ex-home secretary Amber Rudd and former Labour deputy leader Tom Watson, plus comedians including Sophie Willan and Tez Ilyas.
ITV will welcome back former financial opponents George Osborne and Ed Balls, after they sparred well in 2017. They will be joined by former Scottish Tory leader Ruth Davidson, with Tom Bradby anchoring.
Also appearing will be Mr Johnson’s brother Jo Johnson, who stepped down as an MP at the election, Momentum chief Jon Lansman, Leave leader and ex-Labour MP Gisela Stewart, and former Labour home secretary Alan Johnson.