A river of protest placards strung out along the Embankment - Piccadilly Circus in the grip of a giant people-jam. It's the aerial photographs that show the scale of the demonstration in London on February 15 2003 as students and pensioners, trade unionists and religious groups came out to protest against the invasion of Iraq.
Film-maker Amir Amirani's latest project We Are Many delves into these crowds, resurrecting the stories of what brought people onto the streets in an effort to tell "the anatomy of that day," as he puts it.
The global aspect of the anti-Iraq war protests is reflected in Amirani's own February 15 experience.
"On the day of the march I was at the Berlin Film Festival, actually making a film," says Amirani. "When it was all over I went on the march. It was a very big protest, the biggest I'd ever been in. But when I came back to London my friends told me how big the demo there had been and I felt I'd missed out on something historic.
"Around early 2005 I started thinking more and more about the demonstration. The implications of the march and the consequences of the protests being ignored were of such magnitude that it seemed to me to be a really interesting story."
The failure of the demonstrations to prevent the invasion of Iraq and the fact that Amirani has described his film as the "start of a permanent archive of the events of that day" could lead to the assumption that this is something of a memorial project, a commemoration of an outpouring of energy that has now died away or been diverted into other channels. Amirani believes this is a simplistic view that misunderstands the whole nature of protest.
"These protests and movements aren't like switching a light on or off - we march, we get what we want, we don't march, we don't get what we want. These things take time, they are cumulative," he says.
"I think this march showed the scale of opposition, for the record. A lot of people came out who'd never marched before - they became politicised. And anti-war opinion became part of the mainstream."
Amirani enjoys making "multi-layered" films, which is just as well as this project sounds like the mother of multi-layering. It will take a global view of the February 15 demonstrations inviting contributions from those who marched around the world. These accounts of the protests will be combined with analysis from anti-war activists like Tariq Ali and Tony Benn, and from political leaders in power at the time of the Iraq invasion - "if they'll give me an interview," says Amirani. Funding for the film is being raised by the anti-war movement.
As Amirani speaks it becomes apparent that he is, probably, a rather rare combination of new media geek and old-fashioned libertarian. His interest in the role played by technology in reporting and organising news and protest - We Are Many has a Facebook fan page and a Twitter account - runs alongside his desire to capture those moments when people bang the table, say enough is enough and decide to make their private opinions public. The way millions of these "moments" come together to create a movement, which both generates its own news and is reported on by more established media like the BBC and national newspapers, intrigues Amirani.
"Is protest enough?" he asks. "I certainly think it's vital. Then you have things like non-violent resistance which is a logical extension of protest. Protest and resistance and different groups and strategies interweave and different forms of media are involved at various points.
"The disconnect between people and what is being done by politicians in their name is spread throughout the world. This is a fundamentally important question which I don't see being addressed, at least not in our broadcasting media."
Like all films that cover historical events, Amirani's documentary occupies two time zones - in this particular case, those of pre and post-invasion Iraq. Whoever watches it is likely to have a head full of vivid, sometimes conflicting, images of the carnage caused by the invasion contrasted with the delight of many Iraqis at Saddam Hussein's fall.
Even as he works on what he describes as "one of his dream projects," Amirani has been following the progress of another historical process - the Chilcot inquiry into the Iraq war. Rather than being a genuine inquiry he feels this was planned and run "as a nice spectacle to keep people amused."
Amirani says: "It's called an inquiry which makes it sound like an official public inquiry, but it isn't. The level of questioning is very light and they haven't called any foreign witnesses. I'm not sure how hard they're trying to get answers."
One thing the Chilcot inquiry does reveal is the gradual, cumulative way in which a decision to go to war is usually taken. The results of dozens of backstage meetings and deals build a momentum which starts to look as unstoppable as a fleet of supertankers loaded with the oil many believe was the prime target of the invasion.
Amirani acknowledges that the decision to go to war had been taken long before a single demonstrator hit the streets. Rather than demoralising him, this reality provides the mainstay of his commitment to protest and to his film project.
"In a democracy what are the options open to citizens?" he says. "I believe there is a social contract to maintain - the citizens have a responsibility to the state, but the state has a responsibility to citizens, too. It's our responsibility to try and hold the state to account and make sure it keeps its side of the deal."
Amirani hopes We Are Many will fire up the spirit of protest. He says: "It's important people's voices are not lost. People who've seen the film's trailer say they were re-energised by it. I don't think the protest spirit will ever die, but it needs nourishing."
We Are Many is due for completion early in 2011. View the film's trailer at http://vimeo.com/user3146247