In Henry Wood Hall, a grandiose venue tucked behind Borough High Street in south London, a handful of players from the BBC Concert Orchestra surround Bruza, a 23-year-old rapper from east London. Kitted out in the conventional uniform of hoodie, jeans and trainers, he sways beside the jazz saxophonist Jason Yarde as he rehearses his track "In the Endz". The drummer momentarily trips up as he attempts to match the rapper's nimble flow.
"Easy, John," responds Bruza, with a cheeky wink.
There are only 10 minutes left to rehearse, and Bruza is soon joined by his fellow grime rappers Purple, Pase, Tor and the beatboxer Face for a quick run through of "Streets 4 Eva", the primary anthem of the 70-minute musical, Urban Classic, they will be performing with the orchestra at the Hackney Empire in east London on 16 February. "London life is more frustrating, we're bored of waiting, lyrically we're orchestrating," sing the rappers on cue.
Timpani thunders in the background while a xylophonist rings out a sinister melody. Yarde wants to practise the piece again, but one of the orchestra members politely informs him that their time is up.
The musicians start to pack up, leaving the rappers having to settle for Face, who instantly spits a rhythm. The grime-rap producer DaVinChe takes to the keyboard and Yarde reluctantly picks up his saxophone. Moments later, when the rappers congregate for interviews, rapper Purple reflects on the orchestra's abrupt departure. "I recognise that they're professionals... but for us, it's a bit of fun," he says with a shrug.
No one ever said this collaboration was going to be easy. But so far, the experimental project dubbed Urban Classic has seen the laid-back, spontaneous culture of grime meet halfway with the conventions of a high-brow orchestra, a first in the UK.
Bigga Fish, a not-for-profit youth organisation that helps budding rappers and musicians, conceived the idea with the help of the music event producers Serious, along with Jason Yarde, DaVinChe and the BBC, which will broadcast the finished performance on BBC 1xtra and Radio 3.
"If you look back in the past, there's a grim graveyard full of very, very bad, failed attempts at doing something very meaningful with two very different types of music," explains Charles Hazlewood, principal guest conductor of the BBC Concert Orchestra and, with Yarde, musical co-director of the event.
"If you think of what Elvis Costello and David Byrne have tried to do, you end up with a very worthy idea, but it's been very soapy, pasteurised, middle-of-the-road guff. You always ended up with the same fundamental picture - the orchestra sitting at the back playing fat, sweet, string chords, and the pop music down the front doing their thing looking a bit smug."
Hazlewood says this project made it possible for the orchestra to play a more integral role in such an alliance. "I always believed there must be some way of making a new hybrid - which is generally the sum of the parts of all the people on stage - where there's a sense of collective ownership," he says, "and where the strengths of the disciplines and the particular musical traditions that everyone has in the background are brought to bear and fused in a more interesting way."
It doesn't get more interesting than this. The orchestra has turned DaVinChe's electronic productions into a cinematic soundtrack of the streets, brimming with bizarre sonics, awkward anti-melodies, and a clear urgency that the string section accomplishes only too well. As for the rappers - who are relatively unknown - they relay their tales of inner-city living with the same merciless indifference that's definitive of grime and hip-hop music.
Tor, the only female rapper of the bunch, is less focused on femininity than on battling any dude who's bold enough. Pase and Purple are razor-sharp on the mic and Face, an adept beatboxer, can use his lips to create any sound. Bruza is already well-known within the scene as a skilful wordsmith, but says he was sceptical about working with the orchestra, complaining that its tempo could never match the impossibly hasty grime beat. "I didn't really think that it could work," he admits. Face is less diplomatic. "The orchestra don't improvise," he gripes. "They're like robots."
However, merging grime and classical sounds wasn't new for DaVinChe, and he believed the collaboration would work. "I tell you the truth, I did think I could pull it off because I already had the idea in my head," says the 21-year-old. "I had been using a lot of strings, and a lot of horns, a lot of classical percussion like timpani in what I'd been making before. I'm a very musical producer in the sense that I always try to put chord structures and melodies in the music that I make. So it's been a good progression for me, a natural progression for me."
The only major challenge was arranging the music, a task that has seen Jason Yarde work tirelessly over the past few months. "There are aspects [of this project] that have been done before, but not in the same way or on such a scale," says Yarde, who has arranged for Gregory Isaacs and South Africa's Return to Roots Orchestra.
"It's not unusual for people like Kanye West, who just did a show with strings at Abbey Road, or P Diddy or whoever. It tends to be big names who can command the budget. It's not a problem for them to draft in an orchestra, string section, or a massive choir for a tune or for part of their show. We've not had a particular precedent for what we're doing, so it's not like we have been able to look at an existing model."
The goal of Urban Classic is to change the perception of grime music, allowing both consumers and critics to realise its bigger potential, rather than limiting it by the way it is stereotyped.
"What I love about grime is that there's a real urban grittiness about it, which is what it is about," says Hazlewood. "It always amused me that it has this reputation of being very gun-culture based and therefore bad in a society sense. My sense of grime is that an awful lot of it is not like that or about that at all. The rappers are real poets for a start. They do incredible poetry. Within their particular style, the rhythm that they have - intrinsic rhythm - is fascinating and compelling.
"And they talk about social problems, talk about their own individual problems, and the difficulties and challenges of growing up in an urban environment - but there's a huge amount of beauty in what they discuss and an enormous amount of humour. So it's a very rounded form."
DaVinChe adds, "I ended up coming home explaining to my parents that all of us as young urban kids are sitting down with the orchestra who are older and from a completely different background.
"And we're sitting down and just talking to them and explaining to them about grime, and they're explaining to us what they listen to and we try and compare the two. We've built up a rapport with the orchestra - a really good one. And even they have learnt a lot about not judging by stereotypes.
"I think the media perception of UK urban and black music is that it's a really violent kind of music. But we've shown it's just us making music. The violence and everything has nothing to do with the people that make the music."
Already, there's talk of doing an album and possibly taking the musical around the country. The grime artists reckon the experience of working with an orchestra will change way they record their music. "This is gonna up the levels," says Bruza. "It's gonna make people realise grime sounds good live."
"And once we set the standard, we'll keep going," adds Tor. "And it will still be relatable to people like us."
DaVinChe is also hopeful this won't be the last partnership of this kind. "I hope it opens doors for more collaborations like this," he says. "And I think whole grime genre will come up. "Grime has been using a lot of strings and classical instruments anyway. So I can see that orchestras would be our band - because of the power of our music, giving that film or movie feeling.
"With the orchestra, who just read off a score, we've devised a way of making them stop playing, and start playing on command which is not written," says DaVinChe. "So we've broken the barrier."
"So many British orchestra are like lumps of lard stuck in the 19th century - no imagination, and no creativity really," adds Hazlewood. "But the Concert Orchestra is prepared to embrace, and work so imaginatively in a completely a new way."
The Hackney Empire performance will be broadcast on 1Xtra Live from 12-2am on 18 February and on Radio 3 at 10.15pm on 24 FebruaryReuse content