British Prime Minister Boris Johnson says his government appears to have won a powerful new mandate to get Brexit done.

“At this stage it does look as though this one-nation Conservative government has been given a powerful new mandate, to get Brexit done and not just to get Brexit done but to unite this country and to take it forward,” Mr Johnson said on Friday (AEDT) after winning his seat of Uxbridge.

“I think this will turn out to be a historic election that gives us now, in this new government, the chance to respect the democratic will of the British people, to change this country for the better and to unleash the potential of the entire people of this country.”

“That is what we will now do, and if we are lucky enough to be returned as the exit poll seems to suggest then that work will begin … today.”

Exit polls put Mr Johnson’s party on track to win a majority of 86 seats in the new parliament, giving him the numbers in parliament he needs to deliver Brexit on January 31. It is a thumping result for the Conservatives and would delivery their largest majority since 1987.

The exit poll, produced by three broadcasters – the BBC, ITV and Sky –forecasts Labour to win 191 seats in Britain’s 650-seat parliament. The Scottish National Party is tipped to win 55 seats and the Liberal Democrats 13.

Mr Johnson increased his share of the ballot in his West London seat by 1.8 percentage points, winning 25,351 votes for an increased majority of 7210.

The Tories also made gains in the Midlands and north of England, which have been Labour strongholds for generations. They are on course for their best election result since Dame Margaret Thatcher let the party.

“I hope you enjoy a celebration tonight,” Mr Johnson said in an email to party members after Thursday’s vote.

“You powered this campaign. We couldn’t have done it without you.”

Former House of Commons speaker John Bercow said the projected results pointed to a “phenomenal victory”.

“That would be a phenomenal victory for the Conservative Party and Boris Johnson will feel completely vindicated with the gamble that he took.

“That would be an absolutely dramatic victory.”

As votes were counted and the scale of the victory unfolde, Labour leader Jeremy Corbyn announced he would not lead the party to the next election.

Speaking in his Islington electorate early on Friday, Mr Corbyn said Brexit had contributed to the election result, polarising debate and overriding other issues.

He said he would discuss a process of reflection for Labour, and he would lead the party during that period.

An opinion poll conducted for London’s Evening Standard newspaper found Mr Corbyn was the most unpopular opposition leader since polling began in the UK 45 years ago, giving him “a net satisfaction rating of -60”.

Mr Johnson posted on Twitter 30 minutes after the exit poll results were announced, thanking “everyone across our “great country”.

Thank you to everyone across our great country who voted, who volunteered, who stood as candidates. We live in the greatest democracy in the world. pic.twitter.com/1MuEMXqWHq

— Boris Johnson (@BorisJohnson) December 12, 2019

Labour met the Conservatives’ expected landslide victory with despair by Labour, warning that a majority for Mr Johnson would engulf the UK in a fresh crisis.

“If that is the case then obviously it’s a devastating result for us,” the party’s trade spokesman Barry Gardiner said.

Naomi Smith, chief executive of the Pro-European campaign group Best for Britain said while the exit poll “wasn’t promising, the influence of tactical voting at this election has yet to be revealed”.

“Let’s be clear: a majority for Boris Johnson tonight would engulf the UK in a fresh crisis. There is no Brexit deal, only an agreement to talk about a deal in the future,” she said.

Official results will be declared in coming hours.

In the past five national elections, only one exit poll has got the outcome wrong – in 2015 when it predicted a hung parliament. In fact, the Conservatives won a majority, taking 14 more seats than forecast.

If Mr Johnson’s bet on a snap election has paid off, he will move swiftly to ratify the Brexit deal he struck with the European Union so that the United Kingdom can leave on January 31 – 10 months later than initially planned.

Mr Johnson called the first Christmas election since 1923 to break what he said was the paralysis of Britain’s political system after more than three years of crisis over how, when or even if to leave the European Union.

The face of the “Leave” campaign in the 2016 referendum, 55-year-old Mr Johnson fought the election under the slogan of “Get Brexit Done”, promising to end the deadlock and spend more on health, education and the police.

Conservative Party set to win majority in #GE2019, according to exit poll for BBC, ITV & Sky#BBCElection latest: https://t.co/DtxS5EEsxw pic.twitter.com/BvJtazyOiK

— BBC Breaking News (@BBCBreaking) December 12, 2019

Mr Johnson’s strategy was to breach Labour’s so called “Red Wall” of seats across the Brexit-supporting areas of the Midlands and northern England, where he cast his political opponents as the out-of-touch enemies of Brexit.

While a majority will allow Mr Johnson to lead the United Kingdom out of the club it first joined in 1973, Brexit is far from over: He faces the daunting task of negotiating a trade agreement with the EU in just 11 months.

After January 31, Britain will enter a transition period during which it will negotiate a new relationship with the EU27.

This can run until the end of December 2022 under the current rules, but the Conservatives made an election promise not to extend it beyond that.

-with AAP