It began like this. One day in January 2015 a funereal black block flatly stating “Je Suis Charlie”, began to displace all those little icons of hope, aspiration and the odd cuddly toy as the profile pictures of my Facebook friends. Cartoonists offer a kind of safety valve in the straight-laced French press and like the fools in Shakespeare’s plays are able to say the unsayable. Attacking Charlie Hebdo struck the country hard, as a low blow, beneath the belt. But it didn’t stop there. On the 13th of November that year, inexplicably, because at first I had no idea why it was happening, the profile pictures were changing again to the Tricolor, as fast as wildfire, as fast as a computer virus. This time it had come closer. I’d only recently left Paris to return to Biarritz, and I had walked past the cafes that had become a charnel house on the Canal Saint-Martin on an almost daily basis. My daughter’s oldest friend had had complementary tickets for the Bataclan, but she’d been delayed and missed the concert. We lost one of the guys from the line-up at our local surf spot in Biarritz, who had been in the audience.

The protests were visceral. La Place de la Republic resembled a Delacroix and this was an attack against us, an attack against the kids, an attack against innocence. Even if France has an enduring tradition of public protest, only rarely do the “bourges” hit the streets (‘pace’ soixante-huitards). But they did that night. Now it seems the middle classes are rarely off the streets, and like the Anti-Trump Women’s march which I photographed in Amsterdam these protests are often organised worldwide. And they are, of course, inevitably organised through Facebook and Twitter.

A school shooting at the Marjory Stoneman Douglas High School in Parkland Florida on 14th of February triggered one of the largest protests in US history when an estimated 1.2 to 2 million people turned out for 800 rallies countrywide. March For Our Lives wanted to make the seemingly modest demand, under the circumstances, that background checks be conducted on gun sales and the restoration of the 1994 Federal Assault Weapons Ban. In Portland Or. I joined the march shooting pictures as I worked my way through several thousand students and teachers and parents bearing banners touting snappy one liners like, “No More Silence! End Gun Violence”. But one woman’s placard simply said, as if concision would be too trite, “I lost my brother at Columbine 19 years ago. I’m tired of watching families become a part of this club nobody wants to be a part of”. Driving home the chilling reality of a failed gun control policy to all of us making our way towards Pioneer Courthouse Square on a grey damp west coast winter morning where “Portugal. The Man” were due to play.

If it’s a truism to say social media enables these mass demonstrations to organise with unlikely rapidity then it’s ironic if not surprising, that Cameron Kasky, the high school student and a survivor of the shooting, who was behind March For Our Lives, had to quit Facebook to quieten the death threats he’d begun to receive. Which simply illustrates how social media cuts both ways.

The People’s Vote March last October, and the focus of this exhibition, brought 700,000 people on to the streets of London to demand a further referendum following the June 2016 vote which asked the UK to quit the European Union. Full disclosure: I covered the march not so much as a dispassionate reporter, but as an active partisan. My plan had been to join some of the “British in Europe’ group and the 3million which represents the Europeans living in the UK at Speaker’s Corner. The plan was to march with them to Parliament to hear to the politicians speak, and I imagined shooting pictures of them beneath the statue of Churchill, that great proselytizer for the European project. As the crowd gathered, the atmosphere was gentle, more like that of a very big village fete than what is was in reality; a red in tooth and claw attempt to wrench the levers of power from prime minister May. Clearly these well-mannered family people, these teachers, lawyers, doctors and nurses were not the usual protesting type. An unspoken thought reverberated through the air, “If I’m protesting, then things must be really bad!”.

But if they were not the type to normally to protest, what would provoke them to such measures? Brexit can fairly be described as the most divisive issue to confront the British in living memory, and may yet finish by tearing the United Kingdom asunder. And for a Dutch audience the question is no doubt how on earth has the UK got itself into this position? Politically it seemed impossible for Westminster to overturn the result of the referendum. Why? The will of the people had been invoked and was irreversible. Part of the problem lay in the narrowness of the result, 48% against, 52% for, which became exacerbated when the newly anointed prime minister May drew her red lines excluding freedom of movement, one of the four pillars of the single market. And so effectively ruled out a soft Brexit which the 48% would probably, grudgingly, have accepted.

>Paradoxically, Facebook and Twitter was the mechanism that, as with the March For Our Lives and Je Suis Charlie protests, enabled such large numbers unused to direct action to congregate in London, was also the mechanism that galvanised the other side. And arguably drove the anti-Europe lobby to victory. The campaign was unusually vicious and in the aftermath of the vote, absurdity piled upon absurdity to levels that might have been imagined by Lewis Carrol. Not least the recent high court judgement, which held that had the referendum been binding, (as it became to all intents and purposes), then it would have to be annulled as a consequence of the huge and illegal overspend by the official Vote Leave campaign. That spending was linked to Cambridge Analytica and the alleged misuse of Facebook user data which was employed to target voters in the final days of the campaign. But the referendum couldn’t be legally challenged, according to the court, because the referendum was not binding. Meanwhile, the unofficial Leave EU campaign, which was fronted by Nigel Farage and funded by Arron Banks, is currently the subject of a criminal investigation into the source of its funding and the suspicion that that might be Russian.

Social media has had much the same effect on people as pheromones has on columns of ants, driving them to common purpose, reinforcing their point of view and sometimes their prejudices. As I say, it also explains why so many people who rarely come together had done so on the 24th of October. And as we waited in the bright autumn sunshine and quite soon Park Lane became log jammed with people. I left the “British in Europe” and the “3million” groups behind and climbed over the fence into Hyde Park to skirt around the demonstration planning to take pictures as the march moved forward. Now the enormity of the crowd became clear. The march was unable to move forward due to sheer numbers. I used the underpass to cross into St James’ and could see thousands of people simply standing still all along Piccadilly. It wasn’t until I arrived at Whitehall, near Downing St, a distance of about 4 kilometres that the march began to move. And the question is, did all those people make any difference?

Perhaps. Prior to the march the tendency had been in media like the BBC to dismiss calls for another vote as sour grapes on the part of the losers, “We won, you lost, get over it” cried the leavers. John Humphries, doyen of BBC’s flagship radio news program, “Today” described demands for another vote as “increasingly ludicrous”. But the sheer numbers of people who showed up, caused the detractors to draw breath. Pro Europe politicians began to call for another referendum with more confidence. Last week both major parties split on the issue and partly as a consequence, last night finally the Labour leadership also officially adopted the policy. Yesterday the betting odds on another vote were 9/4 on. Today they’re 5/2.