Video report by ITV News Political Correspondent Carl Dinnen
Former deputy prime minister Lord Heseltine led a cross-party alliance in calls for a second Brexit referendum.
The Tory grandee said they were “British patriots” fighting for “Britain’s national self-interest”.
He was joined by politicians from Labour – including frontbencher Rosena Allin-Khan – and Liberal Democrat leader Sir Vince Cable.
Green party MP Caroline Lucas and Plaid Cyrmu leader Adam Price also addressed the rally in London’s Docklands, organised by the People’s Vote campaign and the pro-EU Best for Britain group.
Tory former minister Philip Lee told the crowd: “A People’s Vote is the best hope that we have of reuniting our country after this sorry episode.
“Let’s grasp this opportunity, let’s take back control, let’s have a People’s Vote.”
Harry Potter star Jason Isaacs and Happy-Go-Lucky actor Eddie Marsan also took to the stage at the rally.
Lord Heseltine told the event: “The Brexiteers, they call us traitors. I refute that charge.
“We are the British patriots, we are the ones fighting for Britain’s national self-interest.”
He added: “It is the Brexiteers who seek to belittle us, to undermine our influence, to slam windows, close doors with unrealistic claims of freedom and the delusions of sovereignty.”
Mr Price told the rally the Brexit debate was a “parliamentary tug-of-war, perched on the edge of a precipice”.
“Mrs May wants us to abseil to a ledge half-way down where we will spend the next 10 years in a sleeping bag tethered to the cliff face.
“Others want us to recreate Boris Johnson’s famous zipwire moment, but this time without the helmet, without the harness, even without the zipwire – just two plastic Union Jacks fluttering in our hands as we plummet to our fate.”