Moshpits, spasmodic dancing and shouting the word “brap” are not common features of Labour party rallies. But on Saturday in Tottenham, north London, that’s how hundreds of young voters chose to celebrate their left-leaning political preference, as they crammed into a converted warehouse to party in the name of Jeremy Corbyn.

The event was organised by Grime4Corbyn, a grassroots campaign group which has set up a youth-targeted website to encourage electoral registration. The campaign was launched after a number of grime stars had encouraged their followers to vote for Labour. In exchange for registering to vote, the campaign group offered free tickets to a secret party, and it was so successful that on the morning of the official Labour manifesto launch, at one point more people were tweeting the hashtag “#grime4corbyn” than “#LabourManifesto”.

Its popularity wasn’t a surprise to Brian, a 23-year-old politics postgraduate nursing a pint in the outdoor seating area. “In a way, I’m surprised something like this hasn’t happened before,” he said. “Grime raves bring out millions of young people across the country, so tapping into that is a great way to galvanise them. Some of these grime artists, if they’re telling you to vote, young people are going to listen.”

“Preach!” Speakers on the Grime 4 Corbyn panel debate. Photograph: © Grime4Corbyn / Joe O'Neill

He was accompanied by 26-year-old video editor Sean, who had voted Green in the 2015 general election, but was swayed by the “positive campaign” Corbyn is running. He liked the idea of the event so much that he signed up without even being a fan of grime. “I’m not even necessarily that into the music, but events like this are just great,” he said. “It’s so brilliant to be in an atmosphere with so many people that have the same sort of vision. It’s just nice to be with like-minded people.”

The event began with an afternoon panel discussion about the link between grime and the politics of Jeremy Corbyn, featuring young entrepreneurs and activists. Bursts of derisory laughter accompanied mentions of the Sun and the Daily Mail’s election coverage, with occasional yells of “preach!” in response to panellists pointing out grime music and Jeremy Corbyn’s shared determination to speak out against urban poverty.

“Part of this event is to combat the fact that he’s being deliberately hounded by parts of the media, to say: ‘Stop saying he’s unelectable! People from poorer backgrounds: we think this is our guy!’” said Sofia, one of the organisers of the 500-capacity event, which also featured a sister party in Brighton.

“Growing up on a council estate in east London, grime music empowered me because it made me feel: We might be from the slums, but we can make amazing music,” Sofia added. “And now we’ve got a politician who says: ‘No! There shouldn’t be slums! In the fifth-richest nation in the world, there’s no reason that you’ve got people in Tower Hamlets growing up in poverty.’ Our whole community is behind that.”

The support for Corbyn among London’s urban musicians shows no sign of abating as polling day grows nearer. Recent viral hits have included a video of an anti-Tory diatribe set to a repurposing of the grime anthem Shutdown and an official Labour campaign video from rising star AJ Tracey. In the last few days, posters have appeared in the marginal Tory seat of Croydon, south London, featuring a photo of chart-topping grime artist MC Stormzy, claiming: “The Tories hold Croydon by 165 votes (that’s literally it) – even your dad’s got more Facebook friends. Stormzy says vote Labour!”

Grime artist @ajtracey is voting Labour to tackle the housing crisis. If you're with him RT now ↓ pic.twitter.com/Rmnj7ySGuN — The Labour Party (@UKLabour) May 29, 2017

The motivation for grime’s support isn’t all pro-Corbyn, though. Some of it is based on anti-Tory worries, according to MC Bantzz, who interspersed a frenetic, bassy set by leading the crowd in anti-Theresa May chants and booing over audio snippets of a speech by the Conservative party leader.

“The link between Corbyn and grime is because we’re both for the little man, so what he says connects with us,” Bantzz said. “But Theresa May – I don’t think she’s ever felt like a little person. Some people who’ve had a privileged life can step outside of it and see what’s going on – that’s not her. Talking about cutting off school meals – why would you want to take that away from kids?

“The way we’re coming together against her is starting to feel like a Marvel film, like we’re The Avengers forming against the bad guy. Every young person here is a superhero and they’re going up against a supervillain. She probably doesn’t think she’s evil, but that’s how it is with villains, innit?”