A massive crowd of over one million marched through central London on Saturday to demand that MPs grant them a fresh referendum on Brexit. The protestors are opposed to Britain’s exit from the European Union.

The Put it to the People march included protestors from across the United Kingdom and many European Union nationals living in the UK, The Guardian reported. However, organisers of the march said it was difficult to give a precise number of protestors.

The protest took place amid growing calls for Prime Minister Theresa May to resign. Protestors were seen holding banners proclaiming “the best deal is no Brexit” and “we demand a People’s Vote”, Reuters reported. Saturday’s march is being considered one of the biggest anti-Brexit protests yet.

Senior leaders from all the main parties joined the march, including Labour Party’s deputy leader Tom Watson, former Tory Deputy Prime Minister Lord Heseltine, London Mayor Sadiq Khan, and Scottish National Party leader and First Minister of Scotland, Nicola Sturgeon.

Labour Party’s Tom Watson told the crowd in Parliament Square that the prime minister’s deal was a “lousy” one, whether you voted for the UK to leave or remain in the European Union.“I can only vote for a deal if you let the people vote on it too,” BBC quoted him as saying. “Prime Minister, you’ve lost control of this process, you’re plunging the country into chaos, let the people take control.”

On Thursday, the European Union decided to allow the UK more time to exit the bloc. The duration of the delay, however, will depend on whether the United Kingdom Parliament votes in favour of the exit agreement. Britain was supposed to exit the bloc on March 29.

Sturgeon said the EU’s decision to delay Brexit had created more time to prevent disaster. “This is now the moment of maximum opportunity – we need to avoid the catastrophe of no-deal and the damage which would be caused by the prime minister’s bad deal.”

The bloc had purportedly agreed to grant the United Kingdom an extension up to May 22 if the British Parliament approves the existing Brexit withdrawal deal, The Guardian had reported. If not, the European Union will give the United Kingdom until April 12 to exit from the bloc. Any delay in Brexit is subject to the approval of all 27 countries of the European Union.

The United Kingdom Parliament had voted against a no-deal Brexit by a narrow margin of 312-308 on March 13. After lawmakers rejected May’s previous Brexit proposal on March 12, Jeremy Corbyn of the Labour Party had called for a general election to allow the public to decide who should lead them into the next phase of Brexit.

Here are some images and videos from the protest:

A puppet head of Britain's Prime Minister Theresa May spearing a representation of the British Economy is positioned on Whitehall outside Downing Street. Image credit: Isabel Infantes / AFP
A protester wears a mask of the Queen at a rally organised by the pro-European People's Vote campaign for a second EU referendum in Parliament Square, central London on March 23, 2019. Image credit: Isabel Infantes / AFP
Supporters of the European Union join the march on Saturday. Credit: Steven Watt/Reuters.