Ten of thousands of pro-European Union supporters marched through London's streets on Saturday demanding a final public vote on the terms of Brexit.
An estimated 100,000 people took part in the demonstration on the second anniversary of the Brexit vote.
The so-called 'People's Vote' campaign is calling for a public ballot that can decide on Britain's future once Britain leaves the EU bloc.
Anti-Brexit defender Gina Miller, who successfully campaigned to ensure the UK could not trigger talks on leaving without Parliament's approval, told the crowd:
"Together we must stand up, demand our voices are heard, demand a people's vote so that future generations can hear us say we did our bit, we stood up and shouted for a country that's together, kinder, tolerant. This is not a time to be silent."
Parliament will vote this autumn on the final Brexit deal, which decides how the UK trades with Europe. But the government has repeatedly insisted that leaving the EU without a withdrawal agreement is a possibility.
On Friday, Airbus and BMW said that if the UK were to leave the EU without a deal, it would be forced to reconsider its long-term position, putting UK jobs at risk.
The march comes amid a poll this week that found 48 percent of people supported a referendum on the final deal, while 25 percent were opposed to it.
Prime Minister Theresa May's Conservative Party does not support holding a second referendum on the final deal.
The protest is part of a 'summer of action' by campaign groups designed to increase pressure on Theresa May and the opposition Labour Party leader Jeremy Corbyn.
Meanwhile, Britain's Foreign Secretary Boris Johnson, who was one of the main proponents for leaving the EU, called for a "full British Brexit" in an article penned for the Sun newspaper.
In it, he wrote that any softening of the final deal, such as continued membership of the single market and customs union, would be unwelcome.