The irony is that, until Riverdance, Irish dance wasn't a big deal for the Irish either: despite a thriving competition circuit, it had spawned no great popular works, no dancers as household names. It has taken an expatriate to spot its potential. Michael Flatley, an Irish American born in Chicago and a world hard-shoe champion many times over, both devised the choreography and supplies the show's star focus. But his chief contribution in Riverdance - against all the odds - is to turn what is basically a form of elaborate clog dancing into a sexy spectacle.
The raw material is not promising: backs ramrod straight, chins up, eyes ahead, arms clamped squarely to sides. The dance happens from the knees down. But take 24 freshfaced young champion dancers, drill them hard, clad them cleverly and set them going to Bill Whelan's pounding techno-trad score to which the thundering of 48 steel-capped shoes adds a thrilling extra dimension, and you turn that severity to advantage. What drives Riverdance is a fine tension between vigour and restraint, creative expression and rigid discipline, between young blood and crusty tradition.
As a soloist Michael Flatley is superb, despite looking as if he knows it, with his blond quiff and carefully unlaced lace-up shirts. His toe- tapping and high-kicking are carried off with the machismo of a matador on speed. When he hot-foots it diagonally across the vast stage, followed closely by a file of girl dancers prancing like fillies doing dressage, manes flying, it could be corny, but it all moves too fast for corn to take root. Yet what other leading dancer has a place in the Guinness Book of Records - for speed tapping?
Tackiness sucks gently at the centre of the enterprise, not least in the back-projections of lush poetic texts and fiery sunsets over emerald seas, and the appearance, for no good reason, of a black gospel band. Perhaps Flatley underestimated how much shamrock a wider audience could take. The second half is severely misjudged, conducting a random mini- tour of world dance performed by bought-in talent - American tap, Flamenco and acrobatic Russian folk dance. Yet the images that linger are the simple star-shapes and circles of Flatley's neo-traditional set dances, and the compulsive jigs and reels of the score. Someone once said that the Irish have the rhythm method but no rhythm. Riverdance proves them wrong.
Apollo, 0171 416 6022, to 24 June.