Louise and David Petts are one of London's best-kept secrets. They gig rarely, as their music crosses categories of new composition, rock, jazz and free improv, although it isn't really any of those things, and the electronics they use can make playing tiny club nights a headache. Yet what they do is perfectly unique, and they continue to stubbornly plough their furrow despite the obvious difficulties it presents.

With fellow saxophonist Adrian Northover, they form the Remote Viewers, for whom Obliques before Pale Skin is the second release on Leo. A very assured piece of work it is, too, with covers of songs by Van Heusen, Tiomkin and Madonna sitting alongside David Petts' trademark compositions. These latter are hard to get at first; they seem deliberately ugly, atavistically complicated and lumpy at the same time. But that, in a way, is what he's after, a music which is built on a severe and distinctly uncuddly framework.

You only have to see a photograph of them, really; they're one of the few British avant-garde bands who have a "look." For them it's a sort of '30s style, all dark suits and drapery, as if T.S. Eliot's bank clerks worked on high modernist sculpture and read Wittgenstein at the weekend. The music has a strong modernist feel, but that's just a part of what they do. They also cover songs by Madonna, for example, not in an ironic, po-mo sort of way but just because they like the chord changes. There's a real sense of enjoyment in this sometimes austere, sometimes noisy but always very disciplined music.

When Northover isn't around, Petts and Petts still make music, this time under the rubric of the Poison Cabinet, and they release about one cassette a year on the General Ear label. As David composes all the music for both groups, and Louise writes all the words, there are plenty of similarities here, but there are a surprising amount of differences, too.

Northover makes up a sax trio in The Remote Viewers, which gives them the opportunity to explore thick, reedy contrapuntal textures. With the Poison Cabinet, there's more emphasis on the electronics and on songwriting. Their release Dark Embrace is, as a result, far more accessible to those coming from a rock background. It's also a good place to hear David's wonderful and much-underrated tenor playing in a more exposed setting, which is always good. This, their fourth cassette, is the best so far; the electronics sound more assured, and the recording quality is, considering the medium, impeccable.

Both releases have moments of sheer beauty as well as the angular compositions for which David Petts is known (and ought to be better-known; this writer likes to think of someone doing a jazz album of Petts tunes, but they're tricky, for sure). "Creatures of Distance" is a lovely piece composed of dissonant, drifting synth chords with saxophones thickening the texture, moving gradually into simultaneous soloing of the sort that the trio do extremely well. Although hard to describe, the music these people make is easy to recommend. Check it out if you haven't already done so.