Angry Brexit protesters swamp London streets as UK Parliament meet to vote on deal

The battle over Brexit has spilled onto the streets of London as tens of thousands of people gathered to demand a new referendum while lawmakers decided the fate of Britain's departure from the European Union.

Protesters waving EU flags and carrying signs calling for Brexit to be halted gathered at London's Park Lane before a march through the centre of the capital to parliament.

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After more than three years of tortuous debate, it is still uncertain how, when or even if Brexit will happen as Johnson tries to pass his new EU divorce deal and plots a way out of the deepest political crisis in a generation.

The protesters, from around the United Kingdom, will march to parliament as lawmakers prepare to vote in the first Saturday session since the 1982 Falklands war.

James McGrory, director of the People's Vote campaign, which organised the march, said ahead of the protest that the government should heed the anger of pro-Europeans and hold another referendum on EU membership.

"This new deal bears no resemblance to what people were promised and so it is only right that the public deserve another chance to have their say," he said.

While Brexit has divided families, parties, parliament and the country, both sides agree Saturday could be one of the most important days in recent British history: a juncture that could shape the fate of the United Kingdom for generations.

Campaigners are confident that the number of people on the streets will rival a similar demonstration in March, when organisers said one million people took to the streets.

A rally this size would be among the largest ever in Britain.