Brad Mehldau/Brad Mehldau Trio, Wigmore Hall, London Jazz Festival

The classical environs of Wigmore Hall provided a perfect setting for Brad Mehldau's London Jazz Festival appearances. There is a sense of occasion to these sold-out concerts. On the first of two all-acoustic nights, this acclaimed US pianist played a solo set, in keeping with the repertoire of his recent Live in Tokyo album. That recording came about by accident. The promoter of a February 2003 gig recorded Mehldau's set, and sent him the DAT. He had just moved to the Nonesuch label, and suggested they release this well-captured concert.

The classical environs of Wigmore Hall provided a perfect setting for Brad Mehldau's London Jazz Festival appearances. There is a sense of occasion to these sold-out concerts. On the first of two all-acoustic nights, this acclaimed US pianist played a solo set, in keeping with the repertoire of his recent Live in Tokyo album. That recording came about by accident. The promoter of a February 2003 gig recorded Mehldau's set, and sent him the DAT. He had just moved to the Nonesuch label, and suggested they release this well-captured concert.

Mehldau has been steadily increasing the frequency of his solo performances. This is an outlet that increases the tendency towards unpredictability; a format that hasn't built up a settled vocabulary. Mehldau doesn't allow his tunes to sprawl, keeping most of his readings down to a tight five minutes. Set free from the rhythmic responsibilities of his trio, Brad is able to unwind; varying tempo, articulation and melodic content in a roving, exploratory manner. His evolution is serpentine: Mehldau tends to maintain a constant rippling motion.

He's at once abstract and focused: delivering the straight tune, but with elaborate decoration. The repertoire encompasses Monk, McCartney and Mehldau himself, going back as far as Gershwin and forward into Radiohead. The latter's "Paranoid Android" is the evening's longest piece; a fitting climax, just before the encores start flowing. Mehldau's first set was filled with greater invention; its second half becoming less focused. Midway, he found a rogue note, and took the unprecedented step of halting; heading backstage in search of the piano tuner who, it transpired, had left the building. Mehldau soldiered on, turning the closing run into a linear rush of rhythmically emphatic, bluesy expression.

Mehldau's princely reputation has been formed by the five-volume Art of the Trio album sequence. This setting is his home; his foundation. The following night, Mehldau's regular trio drew what looked like a jazzier kind of crowd. There are different aspects of freedom. Here, Brad has to respond to the bass and drum structures of Larry Grenadier and Jorge Rossy, but their presence allows him to play in a relaxed and spacious fashion. The volume balance between the threesome is perfectly judged, as Rossy skims his skins with lightness of touch.

Mehldau mixes Cole Porter with Lennon-McCartney, crossing the path from willowy ballads to jaunty steppers. His own compositions are generously interspersed, heading off through a labyrinth. Mehldau seems more personable than in the past, periodically introducing clusters of tunes to the audience. In the solo and trio realms, Mehldau's rich sound is embraced by the Wigmore acoustic, reminding his jazz audience how much a piano can be polluted by the often clumsy amplification of a PA system.