Two very different African-American-rooted vocal styles have a big influence on contemporary jazz singing. One is derived from 1940s and 50s jazz and swing, and fuels the careers of artists including Diana Krall, Jamie Cullum, Clare Teal and Stacey Kent. The other, more particular to the American Cassandra Wilson, has earlier origins in her homeland's folk music and country blues, with an injection of Abbey Lincoln and Betty Carter thrown in.

Christine Tobin, the Dublin-born vocalist, is closer to the latter approach - particularly over the past year, in a spacious, simplified band featuring only guitar (Phil Robson), bass (Dave Whitford) and percussion (Thebe Lipere). As with Wilson, the weight is thrown on to the singer and the songs, and the responsibility seems to have made Tobin a more open, varied and forceful performer.

At the regular Thursday upstairs gig at Tufnell Park's Progress Bar, Tobin struck her best balance between her literary enthusiasms (she often adapts poetry to song, and cherishes words more than most jazz singers), vivid themes and improvisation. On the Belfast poet Paul Muldoon's Horses, she was dreamily evocative over chiming percussion, and the excellent Robson's soft guitar chords, which turned into a Pat Metheny-like solo. Tobin's links to Wilson were more evident in the low-pitched scat on Robson's vamp-based My Boat's Ready, and she found herself in Eleanor Rigby territory on the Latin-tinged Brandy and Scars.

Whitford delivered a briefly cogent bass solo on a sultry but rather reserved Can't Help Loving that Man (Billie Holiday and Bjork, two singers with whom Tobin is sometimes linked, have both performed it), and a closing groover found her swapping crisp phrases with Robson's guitar. The singer is likely to be a guest on Robson and saxist Julian Siegel's Partisans Christmas Party gig at the same venue tomorrow.