This, surely, was both the comeback and the Irish event of the year. Planxty return to London after 25 years, and the old chemistry and magic were still there. When they first formed, in the early 1970s, these four musicians transformed the Irish traditional music scene. Here was an acoustic band that could mix stirring, soulful vocals with wildly experimental settings and virtuoso instru mental work, and do so with the energy of a rock band.

Only the lifestyle has changed. The once-wild members of Planxty didn't allow alcohol in the hall, but their playing and singing were as thrilling and varied as ever. Donal Lunny, Andy Irvine, Liam O'Flynn and Christy Moore have broken up and re-formed twice since the early days. They have seen later Planxty members come and go, have all enjoyed success outside the band, and yet they ambled on like a bunch of elderly friends.

With enormous enthusiasm, they set out to "revive music from the players who came before us", mixing tunes that were dominated by O'Flynn's stirring uillean pipes with ballads that were matched against the delicate inter-play of Lunny's bouzouki and Irvine's mandolin, with Moore adding guitar, sparse keyboards and the bodhran hand-drum. Moore is the Planxty superstar, thanks to his international solo career, but he never dominated here. A burly figure in a black T-shirt, he was in fine soulful voice on old favourites like the murder ballad Little Musgrave, and the glorious, stirring Cliffs of Dooneen, but only allowed himself one of his own songs, the witty St Brendan's Voyage. He constantly swapped vocals with Andy Irvine, who in turn switched from traditional songs to his own poignant West Coast of Clare or a demonstration of eastern European influences.

Planxty could still delight and surprise. They well deserve their three nights of standing ovations at a packed-out Barbican.

· At the Barbican tonight. Box office: 020-7638 8891.