All down to trial and Erard

Gwendolyn Mok has battled against spinal injury to play Ravel on a piano made by Sebastien Erard, the father of the modern instrument. (This when she's not performing in war zones.)

The nice thing about the period-instrument craze is that it's democratic: each forgotten instrumental variant has its turn in the limelight, where it survives - or not - on its merits. The pianist Melvyn Tan may now be sidling back to the modern concert grand, but his long campaign on behalf of the Beethovenian fortepiano has put that eloquent, if antiquated, thoroughbred back where it belongs - centre-stage. This week sees the start of a campaign for another Cinderella of the keyboard - the 19th- century Erard. For when Gwendolyn Mok plays Ravel among the Post-Impressionists of the Courtauld Gallery this Wednesday, it will be on an Erard grand made in 1875 - the year of Ravel's birth, and just the sort of instrument for which he composed.

It was Sebastien Erard who, in 1821, made modern pianism possible with his invention of the "double escapement" action - the device that enabled a note to be repeated quickly without the key having to return to its full height. Without this mechanism, the virtuosity of Franz Liszt's Paganini Studies would have been unthinkable. And Liszt became an "Erard artist", just as key players are "Steinway artists" today.

"When you play an Erard, you realise why Ravel wrote Scarbo," Mok explains, referring to the fiendishly tricky last movement of the composer's Gaspard de la Nuit. "The repetition is so fast, the keys almost go down if you sneeze: you have to work infinitely harder on American and German Steinways. But, at the same time, the Erard gives a bigger range of colour. You hear orchestral timbres which the modern Steinway can't begin to produce."

Mok is a petite Chinese-American who trained at New York's Juilliard School from the age of six, chickened out (her phrase) of the piano game at 18, returned after a four-year sabbatical, and got plugged into Ravel under the tutelage of the veteran Vlado Perlemuter, who learnt his Ravel from the master himself. "Ravel feels like my grandfather," she says. "Working with Perlemuter, I got under his skin." But something that happened recently under her own skin almost derailed her campaign for Ravel - and Ravel-type pianos - once and for all. It's a cautionary tale, and a reminder of the athleticism that piano virtuosity entails.

"I was always rigorous about keeping in shape, playing tennis and swimming and jogging. I also regularly went for massage. One day the phone went as I was being loosened up, and the girl went out to answer it. Then she remembered me lying there, ran back, tripped, and fell on my spine. She knew she'd done something bad, and she panicked. First she walked on my back, then she said, `You're so stiff, I'm going to have to crack your neck.' I said, `No way!' But before I could stop her, she'd done it - and, as I later discovered, herniated a disc in my back."

Mok spent the next few days with severe pain and dizziness. But, since she had a Carnegie Hall concert to give, she dosed up with pain-killers and went through with it. The day after, her left leg began to drag; she was referred to a neurologist, who diagnosed a spinal-cord injury, prescribed a neck brace, heat treatment and Valium, and assured her that in six weeks she would be fine.

"I went back to work with Perlemuter in Paris," she continues. "But the pain just got worse, until I could no longer sit up to practise." She went back to New York, and into eight weeks of intensive physiotherapy. She also went on playing - "but badly, as I was still in recovery". Meanwhile, her marriage had broken down; her husband was the cellist with whom she had for 12 years played professionally. "One way and another, that accident ruined my life." It took more than a year of monastic slog - and a therapeutic removal to London - before she recovered her form.

But "form" for this volatile instrumentalist means more than the mere ability to deliver French classics with brilliance in concert hall and recording studio. For a start, she pursues a parallel career as a teacher. I first encountered her giving master-classes - and setting ferociously high standards - at Dartington last year, and she is on the keyboard faculty at the Welsh College of Music and Drama in Cardiff. "I like being part of one of the `underdog' schools - as opposed to one of the Royals - because it's not encumbered by tradition, and therefore much freer to experiment. And I like the idea of showing London what Cardiff can do."

She has a separate life in showbiz. She frequently collaborates on film scores with Maurice Jarre; she dreams one day of making a soundtrack consisting entirely of Ravel's piano music. She is the (uncredited) pianist on a tango record by Astor Piazzolla, where her sound blends seamlessly with the driving Argentine rhythms. She is the pianist on Jon Anderson's New Age compilation, Change We Must, infusing her harmonics with an appropriately spacey twang. She has an uncannily chameleon talent.

And, like a lot of other American performers of her vintage - born in the late 1950s - she's a mover and shaker. She frequently plays in China, where she is better known as the daughter of her opera-singer mother. Playing in riot-torn Haiti, where the audience braved a curfew to come with candles to listen to her chamber-group, was a defining moment of her life. "I thought, that is why I am a musician. Who cares, at the end of the day, if you get a good or a bad review? Music is not about vanity, it's about giving pleasure. It's about making something right, when everything else is going wrong."

She has organised successful events in New York for the International Rescue Committee, and it is on behalf of this charity, which specialises in war-zone relief, that she has persuaded Citibank to fund her Courtauld Gallery concert this week. On the following day, incidentally, she is pressing Ravel into service for education: an audience of primary pupils will be encouraged to listen, look around at the Impressionist and Post- Impressionist paintings on the walls, and then respond with words and drawings. More power to her Erard.

Mok plays Ravel: Wed 7pm, Courtauld Institute, Somerset House, The Strand, London WC2. Tickets, pounds 15 (including private view and glass of wine), from the Courtauld Gallery Shop (personal callers only) or at the door on the night