London - 25 March 2017

1. Wide of anti-Brexit protesters at beginning of march, waving EU flags

2. Close up child with EU flag

3. Police

4. Protester Laura Hussey with pro-EU head costume

5. SOUNDBITE (English) Laura Hussey, British citizen against Brexit:

"What we're marching for today is what all this is about. It's about tolerance, it's about unity, it's about how we're better together and collaborating on the big issues like terrorism. And I have yet for anyone to persuade me of one tangible benefit of leaving the EU other than some nonsensical desire to go back to some made-up era where everything was better because we were just Great Britain."

6. People posing for photos with US President Donald Trump dummy

7. SOUNDBITE (English) Alina Rocha-Menocal, British-Mexican citizen against Brexit:

"We believe in an open Britain. We believe in diversity, we believe in tolerance, we believe that we're much better united and together. And we believe that we need an informed policy process that is actually thought through. Facts and truth matter. And I do not believe that the whole way the Brexit process has been handled has taken that into account."

8. Various of protestors marching holding signs, with police watching on

9. Various demonstrators laying flowers by makeshift memorial by the House of Parliament

10. Close up flowers with Big Ben in background

11. Various armed police at the protest

12. SOUNDBITE (English) Dave Griffiths, British citizen against Brexit

"I never thought that we'd never come (here to the march). We obviously thought they might cancel it because of the security issue. It was, obviously, we're all very sad about the whole event but as with London yesterday and the day before everybody carries on. You can't let them win basically."

13. Police by House of Parliament's gates, pan to demonstrators leaving flowers

14. Woman placing flower in railing

15. SOUNDBITE (English) Cathy Marsh, British citizen against Brexit

"'I've brought flowers today which I've left on the railings in front of Old Palace yard, in the colours of the EU flag as my mark of respect to those who died here. And also as a mark of thanks for all those who showed here such fantastic bravery during the events here on Wednesday. But I still felt it was very, very important that today's march happened."

16. Various of minute of silence

17. Various of demonstrators listening to speeches, clapping and cheering

Thousands of demonstrators gathered under sunny skies in central London to protest plans for Britain to withdraw from the European Union.

The Unite for Europe march included many carrying EU flags just days before Britain is expected to begin its formal divorce from the EU.

Prime Minister Theresa May plans to trigger Article 50 Wednesday, setting the process in motion. Negotiations are expected to take at least two years.

The substantial march came three days after Wednesday's attack on Parliament. Organizers considered delaying the march but decided to go ahead.

Britain voted in a June 23 referendum to leave the EU.