An Isolde in a million

Christine Brewer is one of the great Wagnerian sopranos. But preserving that voice means often saying 'no', as she tells Edward Seckerson

When the BBC broadcast Wagner's Tristan und Isolde over three evenings in 2002, the consensus was that the Isolde of Christine Brewer was the most affecting and beautifully sung in a generation or more.

Listening to that broadcast was someone with more than a passing interest in those assessments – the legendary Swedish soprano Birgit Nilsson, the Isolde of the post-war years. Brewer still has the letter that arrived from Nilsson only days after the broadcast. It was addressed to "Frau Isolde", and if that doesn't trump all the superlatives dished up by the critics, including this one, I don't know what does.

Nilsson's letter wasn't just an endorsement, it was as if she was passing on the mantle of this and other great Wagnerian roles to a singer whom she admired and trusted. But how Brewer came to meet Nilsson and study with her is only a small part of an extraordinary story. It could be entitled "A Star is Belatedly Born".

We start with that Tristan und Isolde, and will try to articulate what it was about Brewer's singing that so seduced audience and critics alike. Hers was clearly what you might call a classic hochdramatische soprano, meaning a voice of size and reach, with the potential for heroic roles such as those epitomised in Wagner's hefty music dramas – Isolde and Brünnhilde in particular. But Brewer's Isolde was so lyrically sung, and with such succulent beauty of tone, that the bigger and more pressing question was how a singer of "a certain age" had arrived at this iconic heroine with her voice so unscathed. Answer: by often saying "no".

Such an honest answer is typical of Christine Brewer. Anyone further removed from the traditional image of the operatic diva would be hard to imagine. There is something reassuringly homely about her; she laughs readily, exhibits no affectation, and, most tellingly, speaks with wonder about the music that she sings and what it means to sing it. It comes as no surprise to learn that hers was a close-knit Middle American family, that she and her brothers sang for fun, that for years she taught at school-level, and that becoming a world-class singer had never really figured in her plans. She took lessons, but that was "for her".

It was only when Brewer became a paid section leader in the chorus of the Opera Theatre of Saint Louis that people such as Richard Gaddes, who ran the company, and Colin Graham, who was its resident director, heard her potential. Small parts and understudying moved her inexorably to the moment when Graham followed his instincts and cast her in a leading role: Ellen Orford in Britten's Peter Grimes. By then she was pushing 30, and her husband (who has nothing to do with the music business) took it upon himself not to renew her teaching licence. His action might just have changed her life.

So, where did Birgit Nilsson come in? Well, it was the soprano Evelyn Lear, a judge in a competition, who detected "a future Wagnerian" in her voice and tipped her off that Nilsson was giving master classes in Washington, DC. They were fully subscribed, of course, but Brewer made it on to the bottom of the lieder list. There was little chance she would get to sing, but finally her turn came. She sang one of Wagner's Wesendonck Songs (the work with which she will launch the new Wigmore Hall season next Saturday). Nilsson stopped her after a couple of lines. "Where did you learn to sing?" she asked.

Later that night, the call came inviting her to a private lesson the following day. More lessons followed. And then she was selected to join Nilsson's voice class in Germany, where she remembers singing Elsa's dream from Lohengrin, while her mother, sitting proudly next to Nilsson, mouthed, "Isn't she great!".

Nilsson always recognised (indeed, you might say envied) the beauty and warmth of Brewer's voice. Her own voice had more steel in it – a laser-like penetration. And she quickly impressed upon Brewer that it wasn't the size but the focus that was important in the big lyric repertoire. And, of course, focus is compromised by wear and tear. It doesn't matter how big the voice is once it gets woolly and wobbly, said Nilsson. Brewer has always heeded that advice: "I remember her saying, 'Don't ever let a conductor bully you into singing louder than is comfortable, particularly in the middle voice'. And, believe me, there are voice-wreckers out there. I had one conductor who told me he could teach me to sing louder!"

When we meet, Brewer is in rehearsal for her Proms appearance as Brünnhilde in Götterdämmerung. It's a big sing – none bigger. But she'll stick to her guns and sing like a dramatic soprano who believes that she's a lyric soprano. "Act II is so emotional, the scorn of this woman is so intense, that you have to be really careful not to blow it all out too soon.

"It's so easy to confuse emotion with the amount of sound you are producing. I always aim to sing the music, never to punch it out. And, believe me, there's a lot of pressure to do so."

Brewer will sing the entire Ring in a couple of years' time, though she cannot yet say where. Bellini's Norma might be on the cards, too, and, of course, there are the plentiful Verdi Requiems – one next year under Colin Davis, with whom she collaborated so spectacularly as Leonore in Beethoven's Fidelio.

Finally, what advice would Brewer pass on to young singers? Next week, she serves on the jury of the Wigmore Hall/Kohn Foundation International Song Competition. What will she be looking for? "Well, it's more important to me that a young singer sings honestly, with what's in their heart, than how well or how beautifullythey do it. You can work on someone's technique, but not on their soul."

The Wigmore Hall/Kohn Foundation International Song Competition, 1-6 SeptemberChristine Brewer's Wigmore Hall recital, 8 September