An estimated 1 million people flooded the streets of central London on Saturday in favour of a final say on Brexit.
Those in attendance demanded a so-called “People’s Vote”, which would allow voters to choose how the UK exits the European Union together with the option for the country to remain a member.
Organisers People’s Vote said some 1 million demonstrators took part, which they said made it one of the biggest protests in British history. Around 700,000 joined a similar rally in October.
Protestors travelled from across the country, with groups posting on social media. One campaigner took on a 715-mile journey on ferries, trains and buses from Orkney in Scotland.
Large EU flags were flown by people throughout the length of the crowd.
Mariella Frostrup and Richard Bacon, who were hosting a rally in Parliament Square, told the crowds an initial count showed the amount of people taking part in the march had topped 1 million.
The march featured people of all ages who were lead in chants for a “people’s vote”.
Many people wore yellow fluorescent stickers reading “Bollocks to Brexit. It’s not a done deal”.
Politicians including outgoing Lib Dem leader Vince Cable and the London mayor, Sadiq Khan, were in attendance.
Other speakers included former Conservative cabinet minister Justine Greening and ex-attorney general Dominic Grieve, former Tory turned independent MP Anna Soubry, Lib Dem deputy leader Jo Swinson, Green Party MP Caroline Lucas and SNP Westminster leader Ian Blackford.
Scotland’s First Minister Nicola Sturgeon told the crowd Theresa May had pitched “Parliament against the people”.
“If that is your view, Prime Minister, let the people speak,” she said.
She accused May of being “in thrall to hardline Brexiteers”.
Marching bands, whistles, cheers and chants provided a constant backdrop of noise.
The Metropolitan Police did not immediately respond to questions about the number of people in attendance.
Organiser James McGrory said the demo was being held amid a “crisis” surrounding Brexit with less than a week until the UK is due to leave the EU.
The UK automatically leaves the bloc at 11pm on 29 March if laws are not changed to reflect delays agreed last week.
“If you look at what was promised in 2016 it bears no resemblance to the Brexit that is actually being delivered,” McGrory said.
“A people’s vote isn’t an option in this Brexit crisis, it is a solution to this Brexit crisis,” he added
Elsewhere, former Ukip leader Nigel Farage hit out at the London march as he claimed “we are the majority” at a pro-Brexit rally in Nottinghamshire.
Around 200 people attended the rally, the Press Association news agency estimated. The event was part of a march to London by Leave-supporters that began last week in Sunderland.
It comes as a petition calling for the UK to remain a member of the EU by revoking the process by which it can leave gained 4.1m signatures as of Saturday.
The petition, created by a former college lecturer on the official parliament website, stated: “The government repeatedly claims exiting the EU is ‘the will of the people’.
“We need to put a stop to this claim by proving the strength of public support now, for remaining in the EU.”
The fast-growing appeal, now the biggest ever, prompted Prime Minister Theresa May to pour cold water on the idea that Article 50 will be revoked before 29 March.