"We're a kind of British covers band," says Ethan Iverson, the commanding pianist of the Bad Plus, before launching into a jazz trio version of Black Sabbath's The Iron Man. Earlier, as well as their own material, they had performed a cover of the Aphex Twin tune Flim, whose nursery rhyme charm was offset by David King's agitated improv on drums and percussion - an interesting analogy to electronica's angsty soundworld. The group, completed by bassist Reid Anderson, plays together tightly with a grungy, contemporary feel - like an uglier version of EST or the Bojan Z trio. King is a constant source of fascination, similar to drummers Jim Black and Paul Clarvis in the way that he maintains a percussive "running commentary", throughout the most unlikely juxtapositions. He can rock out (as he does for Big Eater and the choruses of The Iron Man) and clamber right down to whispery, barely audible percussion at the drop of a bad hat.

After a North American band playing bolshy UK pop, we had the odd spectacle of a two-thirds US band playing melancholy British jazz. It took Tommy Smith's all-star outfit a long time to warm up, with the leader sounding a little inhibited, both by his loose, over-complex suite of compositions, and by his sidemen: pianist John Taylor, guitarist and bassist John Scofield and John Patitucci, fellow tenorist Joe Lovano and drummer Bill Stewart (who at one point paid tribute to the Clarvis/Black/King school of drumming with a clattery interlude). Fortunately the London jazz festival worked its magic. The packed audience was dying to hear a great performance and finally got it, on Lisbon Earthquake, in the form of a Patitucci bass solo, full of individuality and balls. Sputnik's Tale, which followed, generated much more heat and feeling. Scofield, who seemed uncomfortable with the written charts, contributed a couple of great, Monkish solos. The whole concert, including an encore, was recorded for BBC4.

· The festival runs until Sunday. Details: 08700 100300.