The 1996 Dunblane massacre and the outcry that followed are held up in the US as a textbook example of how an act of terror mobilised a country to demand effective gun regulation.

The atrocity, in which 16 children and their teacher were killed, provoked a wave of national revulsion that, within weeks, led to 750,000 people signing a petition demanding a change to the law. Within a year and a half, new legislation had outlawed the ownership of handguns.

Almost 30 years on, the horrific violence visited on a dance class in Southport has sparked a very different reaction. A reaction that shocked many in Britain this week but which experts in domestic extremism – and especially those who look at the intersection of violence and technology – say is all too depressingly familiar. And in this, our new age of algorithmic outrage, depressingly inevitable.

“We’ve always had radicalisation, but in the past, leaders would be the bridge and bring people together,” said Maria Ressa, the Filipino journalist and trenchant tech critic who won the 2021 Nobel peace prize. “That’s impossible to do now, because what used to radicalise extremists and terrorists is now radicalising the public. Because the information ecosystem is designed that way.”

For Ressa, everything about the violence that erupted on Southport’s streets and then in towns across the country, fuelled by wild rumours on social media and anti-immigrant rhetoric, was deeply familiar. “There’s always been propaganda and there’s always been violence. What’s brought violence mainstream is social media. [The US Capitol attack on] January 6 is the perfect example: people wouldn’t have been able to find each other if social media didn’t cluster them together and isolate them to incite them further.”

The biggest difference between the Dunblane massacre in 1996 and now is a wholesale transformation in the way we communicate. In our instant information environment, informed by algorithms that send the most shocking, outrageous or emotional comments viral, social media is designed to do the exact opposite of bringing unity: it’s a polarisation engine.

“It feels like it was only a matter of time before we saw something like this in the UK,” said Julia Ebner, the leader of the Violent Extremism Lab at the Centre for the Study of Social Cohesion at Oxford University. “This alternative information ecosystem is fuelling these narratives. We saw it in Germany in the 2018 Chemnitz riots, which this strongly reminded me of. And we saw [it] in the US with the January 6 insurrection.

“You see this chain reaction in these alternative news channels, where disinformation can spread so quickly and can mobilise people to take the streets – who are then prone to using violence because there’s this anger and these really deep emotions that are, of course, being amplified. And then, from these alternative outlets, it’s carried on to X or on to the mainstream social media platforms.”

This “alternative information ecosystem” – which includes Telegram, Bitchute, Parler and Gab – flows often invisibly beneath the mainstream media or even social media landscape. It has proved to be a breeding ground for far-right, conspiracy and extremist ideologies that this week collided and mobilised people on to the streets.

“Politicians have to stop saying ‘the real world’ as opposed to the ‘online world’,” Ressa said. “How many times do we have to say it? It’s the same thing.”

For Jacob Davey, the director of policy and research for counter-hate at the Institute for Strategic Dialogue in London, it was “a perfect storm”, with a rising far right in the UK emboldened by recent mass demonstrations and far-right figures such as Tommy Robinson “replatformed” on X while measures to hold hate in check are rolled back.

The issue is that although academics, researchers and policymakers increasingly understand the problem, almost nothing has been done to address it.

“And every year that this doesn’t get fixed, no real laws are put in place against social media, it gets significantly worse,” says Ressa. “And I’ll remind you what [Soviet leader] Yuri Andropov said. He said dezinformatsiya [disinformation] is like cocaine. You take it once or twice, you’re OK, but if you take it all the time, you become an addict. You become a changed man.”

Yet, although the UK authorities in theory understand these threats – in 2021, the head of MI5, Ken McCallum, described far-right extremism as the greatest domestic terror threat facing Britain – the fundamental technological issues have not been addressed.

Seven years after the FBI and the US Congress commenced investigations into the weaponisation of social media by the Russian state – investigations that were ignored or ridiculed by large sections of the British rightwing media – the Daily Mail ran a shocked banner headline this week about a single suspicious account on X, with signs it may be based in Russia, spreading false information, although it is likely that this was only one very small part of the picture.

And there is still little acknowledgment that what we are witnessing is part of a global phenomenon – ­rising populism and authoritarianism underpinned by deep-rooted structural changes in communication. Nor is it fully understood, according to Ebner, how deep the similarities are with what is playing out in other countries.

“It’s very, very similar across the world and in different countries with a rise in far-right politics. No other movement has been able to have their ideologies amplified in the same way. The far right is just really tapping into those really powerful emotions, in terms of algorithmically powerful emotions: anger, outrage, fear, even surprise.

“And, actually, what we see is that there’s a sense of collective learning in the far-right community across lots of different countries. And a lot of it has to do with creating these alternative information ecosystems and then using them to be able to respond or react to something immediately.”

The question is what Keir Starmer will do. Ebner points to the fact that this is no longer about dark corners of the internet: politicians are among those who have been radicalised. “They now say things that they would not have said previously and use dog whistles to the far right, flirting with conspiracy myths that used to belong to fringe far-right movements.”

And civil liberties groups such as Big Brother Watch fear that some of Starmer’s solutions – including a pledge to increase facial recognition systems – involve creating further tech-fuelled harms.

Ravi Naik at the law firm AWO, which specialises in bringing claims against technology companies, said there were many steps that could be taken, such as enforcement by the Information Commissioner’s Office to limit data use, or the police taking action over incitement to violence.

“But those actions are after the fact,” Naik said. “The issues are too vast to deal with on the whim of a new prime minister. These are deep and entrenched questions of power. And they won’t be solved in the midst of a crisis or by kneejerk reactions. We need a real and grown-up conversation about digital technology and the future we all want.”