Diana Burrell premiere Barbican Hall, London
The trouble with first performances is that virtually nobody knows how the new work should sound. So audiences and critics tend to believe that what they hear is what the composer intended, and to judge it from that. In fact the composer may, at that very moment, be writhing in an agony of disbelief.

If only all London premieres were as well prepared as that of Diana Burrell's Clarinet Concerto last Thursday. Since the official premiere in Hexham last year, clarinettist Robert Plane and the North Sinfonia have played it in three concerts - plenty of time for the details to settle, and for a sense of the total musical organism to take shape in each player's mind. It certainly sounded confident: expression was warmly felt and the three sections (or are they movements?) followed one another purposefully.

But then, this is a remarkably confident and clear work. Melodic lines and motifs are sharp, distinctive and often very memorable - like the wheeling brass fanfare figures in the fast first section. Harmonies aren't quite tonal in the conventional sense, but often give the impression of being similarly "grounded". Climaxes happen in the right places - expected, yet somehow surprising at the same time. The ending feels like a real end.

So much for the intellectual substance. Imaginatively, the concerto is just as remarkable. The scoring includes such exotica as roto-toms and sanctus bells, and specifies three sets of "multiphonics" (weirdly guttural harmonics) for the clarinet. But Burrell's use of them is not at all gimmicky. Mostly she relies on the colours of a classical Beethovenian orchestra to create her vivid colours and spacious landscapes. The multiphonics appear just three times, in what one could call the slow movement, at the height of three bizarre crescendos. The members of the orchestra play as if improvising to themselves. The texture thickens and loudens, culminating in the clarinet's sustained gurgling squawks. A vast congregation of birds singing, grunting, whistling together? According to Burrell, it was the sound of cars, people walking and talking, transistor radios heard from a motionless train on an embankment in Streatham, that set her imagination working. Whatever, it's fascinatingly effective and it yields wonderfully to the next section: spiky clarinet, bright trumpets and shimmering sanctus bells. It all adds up to an intriguing and ultimately very likeable work.