Thousands of demonstrators have marched through central London in a loud and colourful protest against last week's vote to leave the European Union.
Most protesters were young adults, and many were draped in EU flags while others waved banners bearing slogans such as "I'm with EU" or simply "Wrexit".
They chanted, "What do we want to do? Stay in the EU," as they marched towards the Westminster political district to a soundtrack of songs such as Rick Astley's 1987 hit Never Gonna Give You Up and Whitney Houston's I Will always Love You.
"I was genuinely stunned on the morning after the vote," said one protester Nathaniel Samson, 25, from Hertfordshire, north of London.
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"I feel deeply uncertain about my future," he added. "I'm on the march to voice my discontentment. I am accepting the result, but it's to show that we won't accept it quietly."
Another, Italian Pamela Zoni, 34, who has lived in Britain for six years, said she was very upset by the result and having second thoughts about taking British citizenship.
"I would like a second referendum," she said. "The first campaign was based on lies, and the margin was so tight: it was not a fair result."
London voted 60 per cent in favour of remaining in the EU in last Thursday's referendum, with younger voters widely in favour of staying in the bloc, but 52 per cent of Britons overall cast ballots in favour of leaving.
Rally organiser King's College graduate Kieran MacDermott said: "We can prevent Brexit by refusing to accept the referendum as the final say and take our finger off the self-destruct button."
Parliament should have the final say on whether Britain should leave, he told the BBC.
The vote to leave has prompted a battle within the ruling Conservative Party to succeed Prime Minister David Cameron who said he would resign after the result.
The main opposition Labour Party has also turned on itself, with most of its MPs in parliament having voted to withdraw support for party leader Jeremy Corbyn after what they saw as his lacklustre contribution to the referendum campaign.
