The visit of the Joanne Brackeen Quartet on Sunday provided an example of jazz with sophistication, wit, fun, elegance and what the critic Whitney Balliet once called "the sound of surprise".

Much of the first four virtues emanated from the leader, one of the finest pianist/composers in jazz, while - for this listener, at least - the sound of surprise came from the group's brilliantly distinctive altoist, Greg Osby. In the process, they gave one of the best jazz concerts of the year so far.

Organised by The Improvised Music Company, it brought what is probably one of the finest current American working groups here for the first time. Individually, they're outstanding. Apart from the leader, who is equally adept giving rein to the romantic and the abstract in her music, the quartet includes a truly gifted bassist and awe-inspiring soloist, Scott Colley, a Cuban drummer, Horacio "El Negro" Hernandez, breath-takingly sensitive in his command of nuance in support of soloist and group - and Greg Osby. The altoist, who I'm told owes a stylistic debt to Steve Coleman, was the wild card in a tight quartet. Brackeen deployed both sides of her musical psyche in her solo exploration of Body and Soul, but what impressed at least as much was something else - the fact that, despite her own great gifts, she leads a quartet with a grasp of dynamics, group empathy and the broad emotional range of the music which is astonishingly controlled, yet open and complete, but always with the feeling that there is more it can say if it chooses. And fun.