It’s moments before their gig and Gigwise is sat chatting backstage with 67 rapper LD (he's the one who wears a mask on stage) about their next mixtape.

"67's going global!" he says with unwavering confidence "You're going to hear music like you've never heard before."  Asked if there were big names involved and he smiles but his lips are sealed. 

His excitement about the future with 67 is more than justified. Even before they go any further, they've made music that feels distinctly their own. Taking Drill - a style of rap birthed in Chicago - as a starting point, and infusing truthful lyrics about their life experience growing up on a council estate in Brixton surrounded by crime, they've earned a feverish fanbase excited to hear something fresh.

Lyrically, it's outstanding. It's the most incisive narrative on London gang culture we've ever seen in music this close to mainstream domination - and the sonics astound.

The bulk of their output is on two mix tapes: the first released in 2015 and the second last year. Their pioneering spirit and unfiltered lyricism has seen them earn more YouTube streams than Skepta, and a collaboration with Giggs, but it doesn't feel long before 67 will be a household name themselves. Subsequently, when DJ Kenny Allsta, who is warming the stage for them and a close mentor for 67, says "you’re here to witness history", he’s not wrong.

The atmosphere inside the Tufnell Park Dome, where the rappers have come to play for free to raise money for music therapy charity Nordoff Robins, is suitably ecstatic. Label executives and promoters look onwards at the future as the 250 who've bought tickets – most of who are in their teens - are the foot soldiers driving their popularity forward every Instagram story at a time.

The appeal of this colossal sounding 67– the speakers are loud  - is each of the six rappers voices weave around each other in a slick orchestrated way; and fit like a glove on top of the 67 bpm beats, which, melodically, have as much of a twisted psychedelic colour as a Hawkwind instrumental; and as much darkness as a Joy Division song. The sound truly stops you in your tracks. 

Of the guitar band parallels, DJ Kenny Allstar agrees: “It’s punk,” he says when I tell him my thoughts on this exciting new UK drill sound.

I then look out and see the odd scrap and tussle in the mosh pit - it's more punk than most gigs I've seen this year. Helping along this visceral reaction with the music is 67’s comradery with the crowd; it's first class.

Their sense of unity within the inner circle is also a brilliant factor of the show. The stage door is nearly as popular as the door to the pit floor and it’s an energising sightseeing up to 60 people on stage with 67 by the end and show. They just don't play by the same rules as most bands; 67 is a family vibe. The sense of community is palpable.

One of the guys bursting out of South London's underground to the mainstream with them is Michael Dapaah. He is a guest of honour tonight, and for their last tune they invite him on to perform his viral hit 'Man's Not Hot' He comes on stage in his parka jacket (Liam Gallagher' recently gave him a tweet of approval) in a sweaty club to blast out the most hilarious rap in recent memory. You can watch the clip above and see that 67 gigs are the way forward.