All hands to the joanna

Joanna MacGregor plays pieces that even the composers never thought humanly possible.

For subverting composers' intentions, Joanna MacGregor's Queen Elizabeth Hall recital on Sunday afternoon must surely take the biscuit. Bach's toweringly complex Art of Fugue was written as a musico-philosophical exercise, and not designed for concert performance. Most of Conlon Nancarrow's Studies were written for the player-piano: no player with a mere 10 digits could dream of rendering the multiple layers - and disparate rhythms - of their jazzy contrapuntalism. So a big hand - no, eight big hands - for this intrepid keyboard virtuoso, as she limbers up for the challenge. But how will she do it?

I find the answer in a Bristol church which doubles as a recording studio. Here MacGregor, equipped with headphones, is delicately punching out the contours of a Nancarrow canon. The headphones give her a pulse to steer by: the other pulses emanate from her seemingly subdividable brain. Even the sound engineers are impressed: most of the takes are immaculate, as each new track is added, and the canon emerges in its labyrinthine glory. This is for a CD, but the strategy for the QEH concert will be no different.

How has this come about? MacGregor first heard the work of the reclusive Nancarrow - hounded out of his native America after fighting on the Communist side in the Spanish Civil War - 15 years ago, and was instantly intrigued. "It was witty, enormously energetic, and had all the formality of a Bach fugue." Nancarrow had to devise his compositions without benefit of a computer - hand-punching his piano rolls, he averaged eight seconds of music for 10 hours of labour - but MacGregor believes his art was more rigorous as a result. Dry sticks like Pierre Boulez didn't see the point, but receptive modernists like Gyorgy Ligeti have found him a mine of inspiration. "Nancarrow," says MacGregor, "is one of the most influential composers of the century."

For years she wrestled with the problem of how to present his work, toying with the idea of getting three pianists to play his Boogie-Woogie Suite as part of the new-music festival she defiantly staged when the old Almeida Festival was axed. "But three pianists wouldn't have been enough - for some studies you'd need a whole row of pianists coming up on stage. I dreamt up a galaxy of jazz and classical pianists, rather like the dream Nancarrow once had, of going to heaven and finding this fantastic gathering of Art Tatum, Erroll Garner and Fats Waller all jamming wildly together."

Her dream didn't materialise, but an invitation to record Bach's Art of Fugue prompted a more practical thought. Normally, she says, pianists either duck out of the climactic four-handed mirror fugue - note-for-note the same, whether played forwards or backwards - or drag in a friend to help. "But to say 'Come and play this extra part' is just insulting. So I decided on multi-tracking. Then it occurred to me that that's how I could do Nancarrow, who is in any case Bach's 20th-century successor."

Nancarrow is now 83, crippled by strokes, and holed up in Mexico City; his wife Yoko is his only link with humanity. MacGregor wrote requesting permission to perform the unperformable, sent some of her CDs to prove her bona fides, and finally got a yes. "This," she points out, "was a great act of faith on both sides. They didn't know what I would do, and I was jumping into something totally unpredictable."

But one of Nancarrow's canons is based on the square root of 47. How can an audience possibly hear that? "You can't. Not even the player can bring it out clearly. But the same could be said of the Bach, where you sometimes get the music going simultaneously at four different speeds. You have to see it visually, on the score." Or on a screen. For, in Sunday's concert, MacGregor will play beneath four juxtaposed videos, three of which she has pre-recorded. "You will see what you are hearing."

An interesting enterprise - but then MacGregor is an interesting woman, with a decidedly off-beat background. Born 37 years ago to Seventh Day Adventist parents in Willesden, she was educated at home with her younger brother and sister until she was 11. When she finally got to school, she found that academically she was streets ahead. "My education had been incredibly intensive, and I applied that training later on to playing the piano, which is an equally isolating thing. I had always played, but having no one to compare myself to, I had no idea if I was any good."

She went to Cambridge, where she became a flamboyant punk and immersed herself in theatre work with, among others, a fledgling composer called George Benjamin. Spotted by a Royal Academy professor, she was taken on for lessons, and did two years there as a post-graduate, financing herself for one of them through her earnings as composer for a Channel 4 series whose name she now forgets.

She may be the Academy's biggest success story in years, but while she was there, the diversity of her activities was frowned upon - a matter on which she has trenchant views. "The training of young pianists is appalling. Here are some very hard pieces, they say, now go away and learn them, and we'll see if you make it or not. Ridiculous! It's just setting people up so they can go and commit suicide." Her big break came when she was selected for promotion by the Young Concert Artists' Trust; her first commercial recording was of her own transcriptions of Erroll Garner and Thelonious Monk.

Her recordings to date range from Ives to Gershwin, Ravel to Messiaen, Scarlatti to Satie (about whom she has written a radio play), and she regularly performs on the jazz circuit. Teaming Bach with Nancarrow is a typical ploy. "When I play unfamiliar music, I often have in my head the sound-world of a composer who may be more familiar. With Art Tatum I use the same touch as I do for Rachmaninov. If you approach a piece as though it comes from Mars, and you're from Venus, it can be a problem both for you and the audience." She's even turned her childhood immersion in spirituals to good account, with a score for the medieval Mystery Plays which she and her theatre-director husband, Richard Williams, are due to restage in a London church in July.

She's a constant champion of the new, believing that there is an enormous amount of good stuff being written, and that all that is lacking is the will, on the part of many musicians, to play it. She came back from a recent Johannesburg tour laden with music which she wants to air in a concert: South African composers are in a prolific phase. Two weeks ago, she premiered a new Birtwistle piece, Slow Frieze, on the South Bank: Birtwistle, incidentally, is one of the composers she wants to rope in for the series of piano-tutors she is currently writing for Faber. "Starting with six-year-olds, and going up to Grade VIII. I like the idea of going to composers and saying, 'The pupil knows these rhythms, and these notes: what can you create with them?' "

She practises eight hours a day, much of it at quarter-speed. "It does you good to let the music enter your body in a profound way, in slow-motion, when so much of life is in fast-forward." And she makes it a point of honour not to be finicky about the conditions in which she has to perform: Glenn Gould, a pianist she venerates, is an awful example of what can otherwise happen. "I think he retired from the concert hall because he was just too emotionally fragile. Once you start cancelling, there's no reason ever to stop - there's always something which is not quite right."

Does she ever suffer from nerves? "Sometimes, but not over technical things. Memory is the fear, and I play most of my repertoire from memory." Including the Art of Fugue? She laughs. "Not likely. It's too good a piece - and too long - to take that sort of risk with."

n Joanna MacGregor's new CD, 'Counterpoint: Bach's Art of Fugue, plus Nancarrow's Three Canons for Ursula, and Studies for Player Piano' is released on Monday on Collins 70432. Her live recital of the same programme is at 3.30pm this Sunday at the QEH. Booking: 0171-960 4242

n The Mystery Plays at the City of London Festival: 4pm/7.30pm Sundays 7 and 14 July, St Bartholomew the Great, Smithfield EC1. Booking: 0171- 638 8891