Most people I spoke to agreed that technology companies probably wouldn’t take any notice of this kind of protest. “I don’t think that the pressure on companies will ever work,” Maxime Fournes, the global head of Pause AI, told me when I bumped into him at the march. “They are optimized to just not care about this problem.”

But Fournes, who worked in the AI industry for 12 years before joining Pause AI, thinks he can make it harder for those companies. “We can slow down the race by creating protection for whistleblowers or showing the public that working in AI is not a sexy job, that actually it’s a terrible job—you can dry up the talent pipeline.”

In general, most protesters hoped to make as many people as possible aware of the issues and to use that publicity to push for government regulation. The organizers had pitched the march as a social event, encouraging anyone curious about the cause to come along.

It seemed to have worked. I met a man who worked in finance who had tagged along with his roommate. I asked why he was there. “Sometimes you don’t have that much to do on a Saturday anyway,” he said. “If you can see the logic of the argument, it sort of makes sense to you, then it’s like ‘Yeah, sure, I’ll come along and see what it’s like.’”

He thought raising concerns around AI was hard for anyone to fully oppose. It’s not like a pro-Palestine protest, he said, where you’d have people who might disagree with the cause. “With this, I feel like it’s very hard for someone to totally oppose what you’re marching for.”

After winding its way through King’s Cross, the march ended in a church hall in Bloomsbury, where tables and chairs had been set up in rows. The protesters wrote their names on stickers, stuck them to their chests, and made awkward introductions to their neighbors. They were here to figure out how to save the world. But I had a train to catch, and I left them to it.