Somebody in the audience barracked Cassandra Wilson to sing a standard on her London Jazz Festival show on Monday. They must have had a long memory - the charismatic, blues-rooted singer from Mississippi last released a standards album in 1988. Briefly, and good-humouredly, she complied, with a snippet of The Folks Who Live On the Hill. But the rest of Wilson's performance made it clear that she has had other priorities for a long time.

Her set began like a Scandinavian nu-jazz show (her latest album, Thunderbird, shifts her to a more electric setting than formerly), all hooting horn sounds and trickly keyboards, before she slipped her lustrous contralto into a building groove on Jakob Dylan's Closer to You.

A rougher, driving energy took over for Willie Dixon's I Want To Be Loved, and Time After Time (its lyric stretched with gentle wilfulness into soft collisions with the harmony) brought one of several haunting variations from harmonica player Gregoire Maret. The diversion into The Folks Who Live On the Hill obliged Wilson to sing almost unaccompanied, emphasising how rich and nuanced her voice remains. The funky Go to Mexico then brought the real agenda back.

Though she undoubtedly has more sophistication and depth than the current commercial programme requires, it was a much more vivacious Wilson performance than the sometimes muffled ones of recent years.

· The London Jazz Festival continues until Saturday. Details: Londonjazzfestival.org.uk