Exit poll: Boris Johnson on course for strong 86 majority as SNP surge to landslide in Scotland

The First Minister tweeted: "Exit poll suggests good night for @theSNP - but it is just an exit poll and there are many marginals, so let's just wait and see. What it indicates UK wide though is grim. #GE19."

The joint BBC/ITV/Sky poll, released as the ballot closed, put the Conservatives up 50 on two years ago at 368 seats, which would give the party its biggest majority since Margaret Thatcher’s in 1987, and Labour on 191, a fall of 71, which would be their worst result since 1935; even worse than Michael Foot’s landslide defeat of 1983.

Such a result would put a huge question-mark over Jeremy Corbyn continuing as Labour leader.

The Liberal Democrats, meanwhile, were put on 13, just up one seat on 2017 and which would mark a very poor performance for the party, which had put such store in gaining votes and increasing its seats on the back of their push to Remain. Again, the Lib Dem performance will raise big doubts as to whether or not Jo Swinson could continue – if, that is, she could hold onto her East Dunbartonshire seat.

A projection of 55 seats for the SNP would mean some parties in Scotland would have just a single MP as they did in wake of the Nationalist landslide of 2015.

The pound soared against the dollar and the euro in wake of the exit poll predicting such a large Conservative majority. A pound was up 1.85 per cent to 1.342 dollars and up 1.09 per cent to 1.202 euros within minutes of the announcement.

Labour peer Stewart Wood, a former adviser to Ed Miliband, tweeted: "For 30 years the conventional wisdom was that the Tory Party would be mortally split by the national question of EU membership. Turned out that it is the Labour Party that suffered the most."

Polling expert Michael Thrasher said Mr Corbyn would go down as "one of the worst leaders in Labour's history".

Mr Thrasher, from the School of Sociology, Politics & Law at the University of Plymouth, told Sky News: "The Conservatives have been heading for a clear majority all day long. It really is a remarkable election victory for Boris Johnson, a majority of 86 seats.

"For Labour it really is an appalling election result and possibly its worst performance in any general election since the Second World War. So Jeremy Corbyn, I'm afraid, will go down as one of the worst leaders in Labour's history."

Described by all sides in the campaign as the most important general election for a generation, this was the third election in five years and the first December poll for almost 100 years.

A total of 3,322 candidates stood across the UK's 650 parliamentary seats today.

During the day constituencies across the UK reported the longest queues seen at some polling stations for years, sparking suggestions of a Remainer “youthquake” that would threaten Mr Johnson’s chances of getting a Commons majority and scupper his attempt to lead Britain out of the EU next month.

Ahead of the November deadline to register to vote, some 3.1 million applications were made; which the Electoral Reform Society said was almost 900,000 more than in the same five-week period before the 2017 election.

However earlier, an Ipsos Mori poll of more than 2,000 people conducted between Monday and Wednesday suggested the Tories enjoyed an 11-point lead over Labour, which would put them on course for a Commons majority.

Yet the result remained uncertain as the snapshot showed one in four voters admitted they could still change their mind.

The polling research for the London Evening Standard put the Conservatives on 44 per cent, Labour on 33, the Liberal Democrats on 12, the Greens on three and the Brexit Party on two while "others" would take a vote share of six per cent.

Ben Page for the pollster pointed out how the snapshot showed the Tories retaining 85 per cent of their voters from 2017 while Labour had kept 79 per cent.

"Age pattern seen at the 2017 election has repeated. Labour hold a 26-point lead over the Conservatives among 18-34s whilst the Conservatives hold a 37-point lead with those aged 65+."

However, the great unknown as the polls closed was how much tactical voting there had been.

Called because of Brexit, the election’s final numbers would finally show the extent to which people abandoned their normal tribal loyalties and voted either for Brexit or Remain-supporting parties and just how widespread tactical voting actually was.

Many people had already put a cross for their favoured candidate by voting by post; more than seven million people used a postal vote in the 2017 election.

Ahead of the poll several big names were tipped for a possible shock departure from Westminster, including -

*Dominic Raab, the Foreign Secretary, who in 2017 in the constituency of Esher and Walton secured a 23,000-plus majority but the Lib Dems have targeted the Surrey seat as their possible gain of the night and were hoping for a “were you up for Raab?” moment.

*Dennis Skinner, the 87-year-old Beast of Bolsover, could fall foul of the Brexit effect as the former Derbyshire mining seat voted heavily for Leave; he once enjoyed a 27,149 majority but in 2017 had one of 5,288.

*Iain Duncan Smith, the former Tory leader, the MP for Chingford in Essex since 1992 was targeted by the left-wing campaign group Momentum, which launched an #unseatIDS campaign in retaliation for the Universal Credit reforms, which he introduced as Work and Pensions Secretary.

*Caroline Flint, the former Labour Europe Minister, has held Don Valley since the Blair landslide of 1997 and despite her being pro-Leave the Tories were hoping to cause an upset based on Labour Leavers lending their vote for Brexit.

*Chuka Umunna, the Labour-turned-Liberal Democrat, tipped as a future Lib Dem leader, swapped Streatham for the Cities of London and Westminster seat but polling suggested the Tories would hold onto it.

*Theresa Villiers, the Environment Secretary, had a slender 300-majority and was predicted to fall foul of Labour Remainer Emma Whysall in what is a pro-Remain north London seat.

Earlier in the day, all the party leaders – barring Nigel Farage, who voted by postal vote – were seen arriving to cast their ballot at a local polling station, braving the cold, damp and windy December weather.

However, the Prime Minister declined to vote for himself in the Uxbridge seat he is seeking to represent and, instead, visited the polling station around the corner from Downing St together with No 10 dog Dilan.

He left the polling station at Westminster’s Methodist Central Hall around three minutes later after posing for a picture with his pet.

In north London, Jeremy Corbyn, accompanied by wife Laura Alvarez, was greeted by a small number of supporters as he arrived to cast his vote in his Islington constituency.

A protester dressed as Elmo, a character from children's TV programme Sesame Street, was restrained by security guards as she tried to approach the Labour leader as he entered the polling station.

As the woman in fancy dress argued with security and police, Mr Corbyn said: "Hello guys, can we stop the arguments, please?" He later posed for photographs with well-wishers.

Nicola Sturgeon, the SNP leader, cast her vote in Uddingston alongside her partner Peter Murrell as well as the party's Glasgow East candidate David Linden.

Jo Swinson, the Liberal Democrat leader, was accompanied by husband Duncan Hames, as she visited her local polling station in East Dunbartonshire.

Elsewhere in some parts of London, “unprecedented” queues at polling stations were recorded with people having to queue around street corners in some places.

"I've voted at the same station and time for eight years but have never had to queue before," said Craig Fordham, 45, from Putney, who had to wait for 15 minutes.

Chris Schofield, 27, who queued for 20 minutes in the Bermondsey and Old Southwark constituency, noted: “It's about 20 times busier than it was in 2017 and for the locals and Euro elections. Atmosphere is very London: orderly queueing and no-one is talking to each other."

In Streatham, Alixe Bovey said she queued for 35 minutes. Sharing a photo of the queue outside her local station, she tweeted: "In 20 years of voting in Streatham Hill, always at about this time of day, I have never encountered a queue of more than six or seven people. What is going on? The tailback is right up the road now."

Wandsworth Council, which covers the Labour-held marginal seat of Battersea and the Tory-held marginal seat of Putney, said “unprecedented numbers” had turned out to vote.

Meanwhile across the Atlantic, Alexandria Ocasio-Cortez, the US Democratic Representative, issued a pro-Labour call for the UK public to vote.

Sharing an anti-Conservative video originally posted by Mr Corbyn, Ms Ocasio-Cortez tweeted: "This video is about the UK, but it might as well have been produced about the United States.

"The hoarding of wealth by the few is coming at the cost of peoples' lives. The only way we change is with a massive surge of *new* voters at the polls. UK, Vote!"

In other developments -

*Some 200 students in Cardiff have been left unable to vote failing to register correctly; they were told by the local council that their applications had not been registered due to incomplete addresses.

*Labour complained after scores of “illegal and offensive” anti-Corbyn posters went up across the city last night. They read “Would you trust this man with your children?”

*Voters in south east London faced difficulty getting to one polling station after an apparent burst water main caused flooding in the road around it. Hannah Tookey, who waded through the water to cast her vote, tweeted: "It was too deep to wade through the middle, even in wellies."

*A car crashed through a wall outside a polling station in Chichester, West Sussex. Police said no-one was injured and the station remained open for voters.