JAZZ / Aiming for the big apple: This weekend, for the first time in its history, the Proms is to host a full programme of jazz. Phil Johnson reports

Rossini's William Tell overture inevitably brings to mind the galloping television theme-tunes of The Lone Ranger, or the early Sixties series starring Conrad Phillips as the swashbuckling Swiss outlaw. With all this pop- cultural baggage, the music is not an obvious choice for appropriation by a contemporary composer - unless, of course, the aim is to get an easy laugh.

But on Sunday night, in a Prom at the Albert Hall given by the Mike Westbrook Orchestra and Kate Westbrook, William Tell will ring out unapologetically, loud and clear. It will even swing, for Westbrook's version uses the screaming trumpets, rasping trombones and riffing saxophones of classic big band jazz. From the evidence of previous Big Band Rossini shows, the performance - with neighing horns and a funky back-beat - will not be without humour. What is surprising, though, is that William Tell actually turns out to be a very satisfying piece. The rearrangement is less a post-modern deconstruction of the original than a kind of homage to it. Rossini - an unashamedly popular composer - is here treated with respect.

Sunday's concert also represents a homage to Westbrook, who is finally being treated with respect by the world of 'serious' music. It won't be the first jazz performance at the Proms (there have been concerts by Loose Tubes and the National Youth Jazz Orchestra), but it is the first to be given as part of the main programme. But it's an appropriate honour: Westbrook, 56, is among the most serious British composers in any field at present. Few contemporary classical composers have covered so much ground, or worked in as many forms, as Westbrook, a self-taught musician.

The seeds of the Prom invitation were sown when the director of the Proms, John Drummond, booked the Westbrooks' piece The Cortege for the Edinburgh Festival in 1979. After this performance, Drummond remained interested in the Westbrooks, but giving them a Prom to themselves was far from automatic. 'I don't think we were at the top of the list,' Westbrook says, 'but there was a cancellation. At first John Drummond was going to split the night with a classical soprano but that fell through, so he said, 'Why not do it alone?' There also wasn't a lot commemorating the 200th anniversary of Rossini's birth, so he could kill a number of birds with one stone.'

Westbrook is especially pleased to be given the opportunity to perform his Rossini in a classical context: 'We felt it would be interesting for people who really know that music, as they would be able to hear - more than the average jazzer - what we've done with it. It's lovely, romantic music, very moving, very touching and often very humorous as well.'

Westbrook's use of 'we' is not the royal 'we' of the self-conscious artist, but a nod to Kate Westbrook, his wife and collaborator. An established painter with little musical training, Kate Westbrook joined the Westbrook Brass Band in 1974 and has worked with Mike ever since. She writes and adapts texts for Mike's compositions as well as singing and, sometimes, playing tenor horn or flute. (She has also sung with the London Symphony Orchestra in Kurt Weill's The Seven Deadly Sins, conducted by John Harle.)

The Rossini is light relief compared with some of the Westbrooks' other recent projects. Measure for Measure (to be given its British premiere at the Outside In Festival at Crawley on 6 September) was commissioned by the Vienna Art Orchestra, who then thought it too long and too heavy to include in their repertoire. The piece shows how far from what is conventionally regarded as jazz the Westbrooks can go. A collage of verse from the Shakespeare play, whose music comments wittily on Viennese School aesthetics, Measure for Measure is seriously 'serious'. It remains, however, like all of Mike Westbrook's work, rooted in jazz. Duke Ellington is his most constant influence.

It was hearing a record of Ellington's big band that triggered Westbrook's interest in music. 'When I first heard jazz,' he says, 'I had this notion about self-expression and got hold of a trumpet and tried to play. Very gradually I learnt a few tunes and messed around on the piano. I learnt to arrange a sort of three-piece front-line for a mainstream band and went on from there, adding another horn and then, by trial and error, working out how to do things. It hasn't been a disadvantage: you just do things your own way and maybe it gives the work a certain strength.'

Westbrook trained as a painter at Plymouth and Hornsey art schools. He then taught art at a secondary school in Ealing for two years, where Alan Wakeman, then a pupil and now a member of the Orchestra, remembers him coming into class looking wasted, having spent all night playing at Ronnie Scott's 'old place' in Gerrard Street. He was already making albums but still a semi-pro musician. After leaving teaching and concentrating on music full-time, Westbrook has - like most jazz musicians - struggled for a living. ('We want to live a life dedicated to art and while at the moment we're having a fruitful time, in the past we've been close to giving it up.') Salvation has come in the shape of commissions, usually from Europe, but more recently from the UK too. At the moment the Westbrooks are working on an opera for Channel 4 - adapting a short story, Good Friday 1663 by Helen Simpson, and a further opera based on Coming through Slaughter, Michael Ondaatje's book about the life of New Orleans cornet player Buddy Dolden. Other recent works have included a score for the silent film Moulin Rouge, commissioned by the British Film Institute for the Matrix Ensemble, and Bean Rows and Blues Shots, a saxophone concerto for John Harle (recorded by Decca).

Over the 30 years of his career as a composer, Westbrook has justified the critic Geoffrey Smith's recent description of him as 'the John Bunyan of British jazz': a thorough-going non-conformist who has helped start - and then bucked - almost every jazz trend going. He has been involved with free improvisation, jazz-rock and funk, street band music, cabaret songs, and collaborations with drama and dance, yet the results have remained definably Westbrookian. Despite this, his music took a noticeable turn in 1983, when he was commissioned by the Aldeburgh Festival to produce A Young Person's Guide to the Jazz Orchestra. Westbrook prefers the title 'After Smith's Motel' - named for a doss-house in Glasgow - for the piece, and its composition resulted in the discovery of a chord, the 'Smith's Motel chord', which changed the development of his music.

'It was a sound I stumbled across,' he says, 'which is rooted in conventional harmony but which allows for a kind of parallel, superimposed harmony, which is a stepping-stone to a much freer approach to orchestration, and which has spun off in various ways. The way I approach an arrangement now is often not by thinking of a 32-bar pattern and repeating it, but instead using structures that repeat over much longer cycles.' There are traces of it in the Rossini, in London Bridge (the Westbrooks' setting of texts by Goethe, Siegfried Sassoon and others), and in the trio arrangement of Love for Sale. It's comparable to a more classical approach. At a remarkable festival dedicated to Westbrook's music in Catania, Sicily, last month, it was interesting to watch the composer at work.

Looking less like a teacher now than an eccentric headmaster, Westbrook - his tall, heavy figure occasionally crowned by a panama hat - drilled the sometimes unruly pupils of his big band with quiet good humour. Kate Westbrook, meanwhile, charmed the Italian hosts like a headmaster's wife, before transforming herself into a vamp for the evening performances. Of three nights of Westbrook music - performed out of doors in a baroque palace in the city - the most successful was the final evening, which called upon the composer's settings of Blake songs. With guest vocalist Phil Minton leading the ensemble through Blake's 'I See Thy Form', the combination of sublime words, Minton's impassioned delivery and the band's heartfelt playing was quite overwhelming. It was also a throwback to a different era, when in the 1970s, the Westbrook Brass Band toured working men's clubs and trade union venues as part of a radical movement that blossomed briefly within the community arts movement of the time.

The Westbrooks were never Communist Party members, but performed for the Party, along with folk singer Frankie Armstrong and the rock group Henry Cow. 'It was a marvellous period to go through,' Westbrook says. 'We began playing street music with the idea of making music in the community: to present music of quality in a popular framework. I think we rather outgrew that, but we accepted the constraints quite happily at the time.' Asked about the political commitment of his music now, Westbrook hesitates. 'I would still say that the work has always been informed by a Socialist viewpoint,' he says eventually. 'One sees one's work as being part of social change in the broadest sense, with jazz being an egalitarian and democratic music from its earliest origins. But I do think that if you pin me against the wall, I have to say art comes first. These are very dark times. Your first duty is to express what you feel as best as you can.'

On Sunday, Westbrook will create a small revolution of sorts when his Big Band Rossini becomes the first jazz programme in the Proms proper. Perhaps William Tell, outlaw and scourge of the bourgeois Burgomeisters - and even the avenging figure of the Lone Ranger - have a political context too.

Big Band Rossini at the Proms: Sunday 8.15pm Royal Albert Hall (071-823 9998) and live on Radio 3.

Mike Westbrook and the Orchestra of Smith's Academy at the Outside In Festival: Sunday 6 September, The Hawth, Crawley (0293 553636).

Bright as Fire, Geoffrey Smith's eight- part radio series on Westbrook continues Tuesday 4.30pm on Radio 3.

(Photograph omitted)