“I started going to Sefton Park when I was nine or 10, long before the studio, when there was still only the youth club there. Graham arrived when I was about 14 and he began the Basement. The great thing about him was that he asked us what we were into and what we wanted. We were into mischief because we had nothing to do, and no one had ever asked us what we wanted before - that was definitely a first. We didn’t really know what to say, so first we told him we were into sport, and he got a basketball ring. Then we said music and it started off very modestly with a ghetto blaster.

I couldn’t believe it when he decided to get in the equipment and build the studio. There was this music shop in Bristol where I used to go because they had drum machines in there. But they cost Pounds 300. There was no way I could ever have afforded that, so I just used to go in the shop all the time. I drove everyone mad in that shop because I was in there playing the machine all day. The Basement gave me the opportunity to learn properly.

I was fascinated by the music and the techniques, everything about it. Then I found I was there the whole time. Before I knew it I found that I had started producing the other kids, and the next thing I was working there, just as a voluntary thing.

Recently I’ve been so busy working and travelling I haven’t had the chance to go back much. I’ve been a couple of times to discuss with Jane and Graham what they want to do with the Mercury prize money. You know, Pounds 25,000 is not a lot, and they definitely need more, but hopefully it can help them do something useful. I’m relying on them to tell me what they want to do because they are closer to it than me. They are consulting the kids about what they want, too, which is very important.

Even if I can’t get to the Basement, I still know what’s going on. I see the kids on the street when I’m in Bristol, and they keep me in touch. They tell me what’s happening.

Environments like the Basement are so needed. They are essential. They give people a focus. I don’t like to talk about ita lot because it’s not really about me, is it? It’s about them - the kids who use it and the people who work there. That’s what makes the Basement special.”

Upstairs the bare boards and ping-pong tables recall the youth clubs of all our yesterdays. Step downstairs and you enter a state-of-the-art recording studio with a dazzling array of drum kits, guitars and amplifiers. Welcome to the brave new world of youth work.

This is the Basement Project, sited in a rambling Victorian house in a run down suburb of Bristol. It is also the coolest youth centre in the country.

Already the Basement’s open and progressive policy has produced a bona fide pop star in Roni Size, who, with his Bristol-based crew Reprazent, last October beat the likes of the Spice Girls and Radiohead to win Britain’s most prestigious popular music award, the Mercury Prize.

With his untamed dreadlocks, unconventional dress and gaunt, unsmiling face, this 26-year-old doesn’t look like the average patron of the arts. Indeed, based on image alone, cautious parents might warn their sons and daughters to steer clear.

And neither is he the average pop star. When his ambitious and innovative New Forms was voted Mercury album of the year, with the glory came a Pounds 25,000 cheque. The price of a flash new car? A down payment for that luxury yacht? No. He gave the lot to the Basement, where it will be used to introduce more young people from under-privileged backgrounds to modern music-making techniques.

At the awards ceremony, surrounded by some of the most glittering names in pop, Size paid tribute to the place where he learnt to develop the cutting edge dance sounds and his community-based approach to music. “That was my school. I had the opportunity to sit down and learn about something I really wanted to do.” Shortly afterwards, on BBC2‘s Later With Jools Holland, he said the project and its workers had saved him from a misspent youth that could have ended up in a life of crime.

At the Sefton Park Youth Project, which houses the Basement, Size is remembered with affection. His older brother Andrew works there now, and Graham Baker, the youth worker who set up the place in 1990, still refers to Roni by his birth name, Ryan. “He’s been very important to us. He put us on the map.”

Bristol itself was already on the map -- as the capital of “trip-hop’’ - thanks to the work of Massive Attack and Portishead, who also brought home the Mercury Prize in 1995. Last year Size’s debut -- hailed as the first masterpiece of the new drum’n‘bass genre - sealed Bristol’s reputation. Size now runs his own label, Full Cycle, releasing cuts by Bristol musicians.

All of which explains the air of excitement surrounding the Basement.

According to its mission statement, it is “a youth music resource for marginalised young people that combines professional youth work practice with training opportunities in music, technology, sound recording and radio production”.

The words alone do scant justice to the vibrancy of the centre on a busy Friday night, when up to 70 young people are there to use the facilities.

Karlis, a 14-year-old white boy with cerebral palsy, is in “the control room”, mixing sounds on the two decks. His movements are not easy but he grins with confidence as his sounds are processed and come booming back out of huge speakers. Two black youths of similar age, Jacob and Misha, stand over the mixing desk offering encouragement.

Jane Stafieri, the youth worker in charge, is a musician herself (she sings with Moonshot, a local ska band which also includes members of Portishead).

She obviously commands the respect of the young people using the project, but says: “You don’t get respect just because you are older -- you still have to earn it.”

Here for the first time, Tyrone, 14, can hardly believe his eyes. “There’s no way we could do anything like this at school. We do a bit of music but it’s nothing like this.” Leon feels the same. This articulate black 18-year-old with orange hair, combat trousers and nose stud, says: “I’ve been coming since I was 15. I’ve DJ’d at clubs and parties, and if I ever do this professionally it will be because of what I learnt here.”

Sessions on the equipment last 35-40 minutes. All patiently wait their turn.

When Leon takes to the decks he is the most accomplished, a Roni Size in the making, whipping up a sonic storm. As he mixes, sequences and edits, a clutch of teenage girls watch admiringly and a youthful rapper begins to fires off phrases. The girls are not just spectators. They make their own music on a Tuesday at a girls-only night.

Jane Stafieri explains the philosophy behind the project. “We’re helping young people tap into their own creativity for the first time. We have people from special schools but we treat them like everyone else. When I am asked if I work with problem children I say no. I work with children who may have difficulties impacting on certain areas of their life at the moment.”

She is convinced that youth work, because of its voluntary basis, can fulfil functions the school cannot. “Musicians go into schools to run projects like this and it doesn’t work. It’s a different philosophy here because the young people have come to us. It’s non-judgmental and they suss that straight away.

This is the only place some kids can find a positive relationship with an adult. That’s a big responsibility, and you always have to make time to listen. If young people let you into their lives that is very special.”

The latest development is an in-house radio station, which Graham Baker hopes will grow into a wider youth broadcast network. “It’s about giving young people their own voice rather than us speaking for them.” With funding from the European Social Fund, the Basement recently started offering modules in an HNC radio course.

Money is, inevitably, a big issue. Two years ago the centre was under threat of closure and copies of passionate letters to Bristol City Council from young people pleading for the resource to continue are still stuck on the walls of the stairwell. The council made cuts, but the project survived.

Relations with the community are excellent, and the project is increasingly involved in multi-agency work with schools, social services and probation organisations. Marius Frank, deputy head of nearby Fairfield School, says: “It is a model of good practice, gaining national recognition for the way experiential learning is combined with quality youth work.”

Despite the fame Size has conferred on the Basement, Graham Baker remains concerned about the future. “There is still the danger that youth arts work will be further diminished instead of recognised as way of delivering informal educational opportunities to marginalised young people. Everyone says youth is the future. We try to remind them it is also the present.”