Ian Shaw and Claire Martin have as formidable a capacity for deflationary humour as they do for spontaneous music-making. The two British jazz singers were presenting a compilation of the best bits from their own celebrations of the great pop songwriters, from Hoagy Carmichael to Burt Bacharach and Stevie Wonder. The only accompaniment was Shaw's piano, which may not be Keith Jarrett, but was all they needed.

In the first half, Shaw demonstrated how fiercely evocative his bluesy sound can be on a Ray Charlesian account of Carmichael's Georgia on My Mind. He then characteristically undermined any risk of self-importance with a hilarious imitation of a harmonica solo.

Martin's silky, low sonorities breathed their way round the room on The Nearness of You, and Shaw's eerie sliding falsetto resolved a delectably fragile reworking of Skylark. Shaw also risked a tangle with the much-sentimentalised Alfie in the second half, and gave the song a spine-tinglingly impassioned edge.

But the appeal of this pair's consistently engaging performances is in the balance between their consummate skill and the way they inhabit a stage with such unforced informality. In Queen Bee, Martin told the audience that Shaw would be uncorking an especially stratospheric high note, and distributed party-poppers to accompany the window-clattering blast. Stagecraft it might have been, but that did not reduce the exhilaration quotient.