Goldie is the very model of concentration, his wide topaz eyes taking everything in. There’s a massive thunderclap of drums rolling, followed by a spooky whispering, hissing sound from the 70-odd sopranos and altos of the London Philharmonic Choir, the basses come in, quietly at first, their voices gradually swelling to another crescendo, a banging of a metal sheet, the BBC Concert Orchestra builds as one, as the whole choir sings out in full majestic force… and then silence, followed by applause.

The drum’n’bass pioneer, who experienced the harshest start in life, has just heard his first orchestral piece, which will have its world premiere at this year’s Proms. Sine Tempore (Without Time) – only seven minutes, but each one a thrill – is his response to the concert’s theme, evolution; not one big bang but a series of explosions heralding the birth and growth of new life. Just before the orchestra started up, he and his Maestro mentor, Ivor Setterfield, gave each other a quick hug. It was hard to tell from their expressions which of the two men was more excited – and apprehensive.

Straight after the performance – which is the first time the work has been heard, live, in its entirety – the team is back to work, honing and polishing and adjusting. Goldie is hands-on; no question of him not knowing what he wants, as he stands over the huge pages of the score (converted from his own musical “map”). The tempo isn’t quite right for him, so he sings out the notes to illustrate where he wants them to fall. Setterfield jumps in and asks for more “pungency” in the sound, and “protein” from the basses. “It should be looser, but not sloppy,” he says, and refers them to Goldie’s instruction that the sound needs to be “creamy”. There’s a titter at that but not a disrespectful one.

The rehearsal is taking place in Henry Wood Hall, a Grade II-listed converted church, with handsome columns and vaulted windows, which has been used as a recording space by the likes of Leonard Bernstein, Alfred Brendel and André Previn. Goldie has joined their ranks because of his commission on the back of his appearance in Maestro, last year’s hit TV series, where eight celebrities competed for the chance to conduct the BBC Concert Orchestra at the Proms in the Park. Comedian Sue Perkins won, but Goldie – the runner-up – was the undisputed star of the show.

We had met a couple of weeks earlier at his home in Bovingdon, near Hemel Hempstead, in Hertfordshire. He opens the door, flashing his gold-toothed grin and shaking my hand. I’m a bit early so he tells me to make myself at home while his own Man Friday – a role which, until recently, was performed by his kid stepbrother, Stuart, 12 years his junior – fixes him an old-fashioned Mothers Pride sandwich.

It’s a perfectly comfortable home but no rock-star mansion. There’s a slight bachelor-pad feel, with lots of stuff lying around, including a Ducati motorbike (a gift from Val Kilmer) as a sort of sculpture on wheels. The walls are taken up with Goldie’s art – canvases of collages and a large work which looks like a psychedelic reading of a heart-monitoring screen. We sit at a substantial wooden table, at one end of the living room, and Goldie kicks off with a history of the drum’n’bass movement which, frankly, loses me completely.

What is clear is that he doesn’t suffer an iota of self-doubt on this front – “I became the picture boy of the Nineties in terms of the PR machine… that I didn’t employ… because I didn’t need one,” he says. Now 43, he is also knowing enough to be aware that part of his appeal, notwithstanding his talent, was that he had street cred, in spades.

We have barely touched on this, when he’s into the nitty-gritty: “People used to ask me, ‘How can you make music that’s so uncompromising and wear your heart on your sleeve, and bare your soul to the general public?’ and I’m like, ‘When you’re in a children’s home with 25 kids and you’ve gone from foster parent to foster parent, and all these different things, do you think that sitting in a roomful of critics is really gonna make a chink in my armour?’”

This is followed by another challenging stream of consciousness about Goldie’s spirituality, delivered with enthusiasm in his flat Brummie accent, while he endeavours to explain (actually, I’m not sure that he’s all that concerned about my receptivity) how he has exchanged that armour for a more translucent way of being.

He stops off, en route, with the memory of a very old astrologer who lived in a flat above Waitrose in Finchley Road – introduced by his then girlfriend, Björk, a major influence on him – who warned that he was going to burn himself out: “You are burning all the time and you cannot stop giving.” Thence the parallels between him and jellyfish: “If you see them in their environment, not washed up on to a shore, and you think about how ghost-like and beautiful they look, how they reach out with all these different tentacles, all electrifyingly dangerous and pulsating, but overall they just have a spiritual feeling of wanting to be left alone in this ocean… to be able to absorb everything and not just see everything but be able to sense everything…”

You are saying that you are like that jellyfish? “In a funny way, I am a little bit. I think I’ve just learnt that I’ve had to keep the depth around me to survive. If Goldie came along and made Timeless, which he did…” (This was his 1995 album, which went into the mainstream charts at No 7, a first for drum’n’bass.) I stop him abruptly because what interests me is the way he has started to refer to himself in the third person. “My persona has been created by a boy wanting to create a protective shell around himself, but the boy has always been there. When you look at me… [he meshes his fingers together in front of his face, opening and closing them so that his features go in and out of focus]… Goldie’s here but underneath that façade of everything, there’s still this little boy underneath that you can sometimes get a glimpse of.”

When Goldie was that little boy, his name was Clifford Joseph Price and he lived in Wolverhampton with his older brother, Melvin, and their Scottish mother, who was finding it difficult to cope: “She was getting beaten by one boyfriend and my dad was flitting around England, working in foundries in Leeds, not turning up when he was supposed to, disappearing for days and days,” he explains.

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