Take me to your lieder: Bryn Terfel is possessed of a heavenly bass-baritone and the strength of a prop-forward. He locked heads with Edward Seckerson

Bryn Terfel was in the seventh and final week of rehearsal for his first Leporello. He was growing more like Don Giovanni each day - his twin, his alter ego, his conscience, ultimately his better judgement. At least, that was producer Patrice Chereau's current thinking. But Salzburg was getting hotter. And so were rehearsals. Terfel's wife Lesley and newborn son Tomos had arrived in town. He was restless. Impatient for an audience. 'Seven weeks is too long. I know it's good to have the extra time when you are preparing a new role - and Leporello is quite a role . . . so busy, so physical; he's rarely off the stage. But you know, I find that after four or five weeks of good, useful work, producers are inclined to start changing things. They start to think again.' Even Patrice Chereau? Particularly Patrice Chereau.

Terfel is honest enough to admit that he doesn't actually enjoy the rehearsal process. Yes, it had been stimulating - to a point. But now that things were set in his mind, now that he had something definite to build on, the time had come to do it. The orchestra had arrived - 'another blast of energy, another piece of the jigsaw to add to the costumes and scenery'. Now for the audience. Only then, says Terfel, is the performance born. He comes alive with an audience. The feedback, the exchange of energy. He drinks it up. Rehearsal inhibits him. Performing frees him.

But then, we're talking here of an artist for whom instinct is all. A 'natural'. The word has been over- used and abused. But in Bryn Terfel's case, it really does apply. He is, without doubt, the most gifted male singer of his generation. People reach for phrases like 'God-given' to describe the voice. And it is spectacular - born and bred in Wales, the promised land for voices. This one definitely drew its sustenance, depth and resonance from the valleys. A true bass baritone: flexible, far-reaching at the top; weighty, well endowed at the bottom. There's a fortune in that bottom register. Whole areas of repertoire open up to it.

Contemporaries of his at the Guildhall School of Music will tell you that there wasn't much that anyone could teach him in terms of technique and musicianship. Beyond the voice itself was an uncanny awareness of how things should go: an ear for the sound, colour and dynamics of music, a nose for atmosphere. Terfel may not always be able to articulate how he feels about a piece. But it's there. And it will out.

The word has been out for some time now. Since 1989, when he walked off with the Lieder Prize but not the title 'Cardiff Singer of the World'. Dmitri Hvorostovsky took that. But guess whose career is promising greater long-term possibilities? There isn't too much daylight in the Terfel engagement diary, currently booking through 1998. His agent fields a steady stream of offers from the world's great stages. But the man himself remains obstinately level-headed. He appears to have the psychology licked. He refuses to succumb to pressure. No stress, no ulcers equals a long career. He never loses sleep over work, whatever the circumstances. 'Why should I?' he says. You know he means it. But then you begin to wonder: can any sensitive, creative artist really be this well balanced? Is this confidence born of absolute security? 'Funny, I used to think that of Samuel Ramey. But he probably doesn't feel it either. No, I have to work at my technique constantly . . . believe me, just getting across the Grosses Festspielhaus stage here in Salzburg - it's huge - or coping with all the business of Leporello's 'Catalogue' aria, your breathing can go to pot. And when your breathing goes to pot, so does your singing. There's no such thing as absolute security. Not for a singer.'

For a listener, then. When Terfel is in action, the audience breathes easier. There is nothing, it seems, that this voice cannot and will not do for him. In a new recording of favourite Schubert songs for Deutsche Grammophon (who've signed him exclusively), he achieves one of the quietest and most eloquent pianissimos I have ever heard on a gramophone record. The song is 'Litanei auf das Fest Allerseelen' and the line in question reads 'Rest in peace, all souls'. So what are the words and music really saying here? That any sound at all is an intrusion. That's the way Terfel works. He absorbs the sense of what's written and tells it like it is. He's not about to pretend he spends long hours in the library researching, because he doesn't, and he wouldn't claim any great psychological insights. His interpretative strength is in his honesty. The sophistication is in the singing.

'I'm not really a Lieder singer.' What makes you say that? 'It's not really me.' Not even that close contact with the audience? 'Oh yes, I enjoy that . . .' What then? 'It's difficult. Full stop. No, look, I welcome the challenge. It brings you down to earth from the opera stage. It makes you think more about your singing. In Lieder, everything you do is magnified.' But you feel constricted in some way? 'Very much so.'

It's true that Terfel's physical presence, his rugby front-row build and his writ-large personality, take some containing. That's what makes him such a naturally dynamic stage animal. But at his recent Wigmore Hall debut in London, you didn't have to take your eyes off the broad facial expressions to appreciate the finesse of the singing: the subtle shadings, the delicate ornamentations, the effortless ascents into his honeyed head- voice. And when it was all over, he was just warming up. He's the only singer I've ever known sing Schubert's 'Erlkonig' as an encore. And it tells you something about his priorities that he did so primarily to see the audience's faces when the piano pitched into its tempestuous introduction. He's there to enjoy himself. He wants you to enjoy yourself. I doubt he's ever taken himself too seriously. What you see is what you get. What you hear is something else.

One question still burns. Bass baritones of this stature are inevitably summoned to Valhalla. Three years ago Terfel was adamant that the big Wagner roles were at least a decade away. So far he's as good as his word. There'll be no twilight of the Gods just yet. Wotan has been offered and declined. Daniel Barenboim has asked him to consider Beckmesser in Die Meistersinger. Terfel reckons the 'Dutchman' will be his first major Wagner but he's making no promises. Right now he's happy to test the water, and err a little on the wrong side of caution. To that end he's taking on Mandryka in Strauss's Arabella at Covent Garden: 'a big step towards Wagner . . . very definitely a bass-baritone role with an enormously challenging range'. What about the great Hans Hotter's assertion that the key to vocal survival in this fach is never to sing with more than 85 per cent of the voice? He pauses, tactfully. 'Perhaps he could. But I can't. Not now. When I'm performing there's the rush of blood, the adrenalin and I'm away. It doesn't matter how much I want to save myself, I want to sing well. I have to give the full 100 per cent. But then, I'm not singing that repertoire yet, am I . . .?'

So Bryn Terfel's content. He's running his career, not the other way around. He has a new home, a new son, a full-size snooker table on the way. And he's a Welshman. What more could a man want? What is it about the Welsh and singing? What makes it the promised land for voices? One word: tradition. 'It's partly the language,' says Terfel. 'We have seven vowels, it's very open, very singable. But singing always was, and still is, a recreation. Every village has its choirs.' He's quick to stress that it's an amateur tradition. That it's a long road from there to the profession. But that's not the point. The amateur tradition is a breeding ground for professionals. In Wales, people sing. If you've a voice, the chances are you'll find it. Terfel is proudly nationalistic. On Saturday he sings 'Rule Britannia]' at the last night of the Proms. In Welsh? 'Just get me a translation . . .'

Bryn Terfel takes part in the 'Last Night of the Proms', at 7.45pm on Saturday 10 Sept at the Royal Albert Hall, London, and live on BBC 2

(Photograph omitted)