British Prime Minister Boris Johnson and his dog Dilyn leave a polling station, after voting in London on Thursday, in Britain's general election. Photo: AFP

UK Prime Minister Boris Johnson proclaimed a political "earthquake" Friday after his thumping election victory cleared Britain's way to finally leave the European Union after years of damaging deadlock over Brexit.

With all but one result declared for the 650-seat parliament in Thursday's momentous election, Johnson's Conservative party had secured 364 seats - its biggest majority since the heyday of Margaret Thatcher in the 1980s.

The main opposition Labor party suffered its worst performance since the 1930s, forcing its socialist leader Jeremy Corbyn to announce plans to step down, but Scottish Nationalists performed well, raising the prospect of another push for independence.

The pound shot up to its highest level since mid-2018 on hopes for a swift end to uncertainty over how, when - or even if - Britain was going to draw its often rocky five-decade involvement in the European project to a close.

Condemning more than three years of bitterly divisive political wrangling, Johnson vowed in his victory speech to "put an end to all that nonsense" and "get Brexit done on time by January 31, no ifs, no buts."

"We did it - we pulled it off," the pro-Brexit figurehead of the original 2016 EU membership referendum told cheering supporters. "We broke the gridlock, we ended the gridlock, we smashed the roadblock."

Johnson arrived in Buckingham Palace on Friday to receive formal instructions from Queen Elizabeth II to form a new government.

Even some pro-European voters expressed relief at the outcome, which the pro-Labor Daily Mirror newspaper called a "nightmare."

"At least it's clear," said lawyer Gordon Hockey. 

"It's not necessarily what I wanted but at least we know where we stand and Brexit will happen in some form or other."

Parliament's ratification next month of the EU-UK divorce deal will complete the first stage of the Brexit process, but both sides still need to thrash out a new trade and security agreement.

EU Council President Charles Michel said the bloc was set for talks.

The result of Thursday's snap election - the third in almost five years - signals a personal victory for Johnson, a bombastic former London mayor and foreign minister who staked his political career on the vote.

US President Donald Trump tweeted his congratulations on a "great WIN!" and said London and Washington would be able to strike a "massive new trade deal" after Brexit.

"This deal has the potential to be far bigger and more lucrative than any deal that could be made with the E.U. Celebrate Boris!" he said.

German Chancellor Angela Merkel pledged to develop a "friendship and close partnership" with Britain.