You can find a dirty, backstreet tango emerging from the opening sonic blitz of his opera, Powder Her Face; elsewhere, he coaxes from the orchestra a motor horn, a swanee whistle and a danceband record with its needle stuck. He flirts with pop tunes, jazz riffs and atonal squeaks of Berg to get what he wants. But now and again, he goes too far. When he messed around with techno, it nearly finished him off.
"I was composing a piece called Asyla," he explains. "In one section, I wanted to evoke the atmosphere of a massive nightclub with people dancing and taking drugs. So I bought some techno music and listened to it, just quietly, to get the structure rather than blast my head off. I realised that, in techno, you have to repeat things 32 or 64 times. So I tried to orchestrate it one night in my living-room, repeating all these figures over and over, on this massive score paper, 30 staves to a page. At 3am, I went to bed and, as I sat there, realised my heart had stopped beating. I thought, `Christ, I'm having a heart attack'. I rang the hospital and then they sent an ambulance.
"My heart gradually started again, but very shallowly. The ambulance took me to the Royal Free, where I waited for two hours among other Saturday night casualties. And finally a doctor saw me and said, `You hyperventilated'. I thought, `Thank God. It's not my heart, it's just my brain...'."
The Ades brain, and the Ades imagination, have both been objects of awe to music critics since he was runner-up in the BBC's Young Musician of the Year in 1989. "The most audaciously gifted young composer to have emerged in this country for as long as I've been writing about music," said Michael White in the Independent on Sunday. "Ist Thomas Ades der Retter [saviour of] Britischer Musik?" demanded Frankfurter Allgemeine, rhetorically. "It is no longer fair to call him a prodigy," gushed Alex Ross in the New Yorker. "He has become, at 26, a prime mover in English music. His work as composer, conductor and pianist has caused a near total capitulation of critical and popular opinion."
Lunching with Ades should, by rights, be like meeting Mozart at his most precocious and conceited. Amazing, therefore, to find Mr Ades a tremendously engaging, Wildeanly languid fellow who smokes Consulate menthol cigarettes with neither irony nor shame, talks a blue streak in a rumbling basso profundo, and has a booming laugh so reverberative it can probably be picked up on submarine radar. He wears a denim jacket with straining buttons. It's nice to find such a rarefied intellect preoccupied by mundane concerns such as his weight.
"I was a large bloke at school, UCS in Hampstead, and got teased all the time and bullied. I was non-sporting, you see, a) because I was crap, and b) because I found the whole thing so boring. I did aphorisms instead. Every day, I'd put on my iron bra, as they say, and go in ready for battle. When I went to the Guildhall one day, I got really fed up with being the Fat Boy. I wanted to be more beautiful. So I lived on a bowl of soup a day for I don't know how many months. I became very vain, and, of course, laughed at anyone who said you're too thin. Looking back at it, I was actually anorexic. Since then, my weight has been crawling back, and now I'm very, ah, healthy and strong."
Such iron self-discipline does not extend to his work regimen. "I don't have one. I wish I could say I was up at six every morning, work till two, break for half an hour for carpaccio of reindeer and slivovitz, and suddenly one day there it is... But I hate mornings. I can't see what they're for at all. I can't plan. If you try, it doesn't really work. I brood on things for months and months and don't write much."
When composing opera, does he consult the libretto from the start, or when the main themes have been established? "You know how, when they cut a diamond with a laser, they have to find exactly the right point at which to go in? I think making art is a little like that. In Powder Her Face, I wanted to take each scene I'd been given by [the librettist] Philip Hensher and find the point where the whole thing would open up and be the right shape and the right scale..."
Powder Her Face, Ades's first opera, is the work he had chosen to kick off this year's Aldeburgh Festival, of which he is the artistic director. Its subject is the life and disintegration of Margaret, Duchess of Argyll, the sexually voracious and spectacularly unfaithful divorcee. The opera evokes her later years, holed up in a Park Lane hotel, dreaming of the past, failing to seduce the manager who is trying to eject her, and finding herself derided by maids and electricians. Whirling strings and minatory martial taps, a giddy swoon of violins interrupted by stern thuds and claps, suggest an old lady in disarray: her fox furs, her fog of memories of long-lost ballrooms interrupted by the rude arrival of the modern world, the honk of taxis and car-horns outside her window.
The opera has been banned by Classic FM, and had to wait a while to be broadcast on Radio 3, because of its explicit libretto ("Why don't you suck me off until you can't take more?"); Ades, with creditable devotion to realism, gives the Duchess some notes to be hummed when she is unable to sing with her mouth full.
I said I was surprised at the percussive nature of the score, where the strings and brass produce a cacophony of pops, bangs, groans and jangles. "I was trained as a percussionist," Ades explains. "I was told I could be a professional marimba player..." Did he hear everyday sounds and think, `I can use that'? "Oh yes. Like someone putting up scaffolding. There's a bit of scrap metal in Powder Her Face, that is supposed to suggest the untended pipes in the hotel. Like the pipes in her own mind..." He laughs at his own mild pretentiousness. "But all the time, in modern life, there's a strange, otherworldly sheen of noise, and I work very hard to get it into an orchestra."
Born in Highgate in 1971, he wasn't exactly a child prodigy. "I can't ever remember learning to read music," he says. "I was playing so far back, I don't remember when I started. I recall playing bits of Liszt with the right hand. My right hand was very advanced - I could do fiddly- diddly things with it - while my left lagged sadly behind. I was rather a dilettante," he shockingly concludes, "until the age of 11." He studied at the Guildhall and King's, Cambridge, got a double- starred First, and amazed his tutors. He started on the violin ("disastrously"), switched to piano, then "something suddenly went... sort of flash when I was 18, and I thought I really have to do this properly now. Composing, I mean. I'd accidentally fallen into winning piano competitions and if I hadn't started thinking very hard about it, I might have had a nice, modest career as a pianist. But the prospect of playing pieces that lots of other people had already played... I thought `Can't I do more than this? What do I have to do, in order to?' And the answer was: work."
And by God, he worked. Compositions flowed from him as from a divine production line. He produced a Chamber Symphony at 18, and was taken up by the BBC Philharmonic and the Ensemble Modern. Piano solos, works for chamber orchestra and string quartet, song cycles (Five Eliot Landscapes), tone poems (Living Toys), brief pieces for large orchestra (These Premises are Alarmed) and chamber ensemble (Concerto Conciso) - all came flying from his pen in a riot of originality, while full of knowing allusions and homages to tantalise critics. Reviewers mentioned Stravinsky, Berg, Sibelius, and Gyorgy Kurtag as his biggest influences. Were they right? "I've been influenced by all of them," says Ades. "It would be ridiculous to deny it. But by whom most of all? I've got no idea."
He is charmingly indiscreet about his dislikes - such as John Tavener's "pseudo-Byzantine" church music ("I think it appeals to the most wretched thing in all of us - the will to be wretched") - and bracingly rude about the accusations of "elitism" that are routinely suffered by modern opera.
He's going to write an opera about mass audiences and crowds, and power and cults - soon. It will presumably take its place in the queue behind the one he's working on for the New York Philharmonic, then the one for Glyndebourne next year, and yet another for the re-opening of the Royal Opera House. A whole corpus of Ades works is in the pipeline; they will eventually need a Kochel system to collate them all.
What does he want to achieve by the time he's, say, 40? "I want to have changed something." Changed modern music? "No, changed the people who hear the pieces. I've no interest in influencing anyone else's work. I hope I'm not one of those composers who close avenues. If anything, I think I open them..."
We get up to leave. Down the other end of the restaurant, someone scraped their chair back with a terrible screech. "What the hell was that?" I say. Ades considers. "F-sharp, I think," he finally retorts.
The Aldeburgh Festival runs from 11-27 June. Box office: 01728 453543. `Powder Her Face' will be performed there on 11 and 15 June, and at the Almeida Theatre, London, for five nights, starting 30 June. Box office: 0171-359 4404Reuse content