'I wanted something', Heath remembers, 'that would give the sound of running water. I talked to the percussionist who would be performing in the piece, and he suggested, 'Why don't you get the players to throw pebbles in a bucket?' I tried that, but I found it made a sort of 'donk' sound that I didn't want - I was doing this at my mother-in-law's at four in the morning. Then I put my track suit in the bottom of the bucket, and when the pebbles hit the water, it was OK, but it still wasn't quite right. I thought, 'To hell with it' and I took the track suit out of the bucket - and it sounded fantastic. There was the running water, and as the drips got slower and slower, different rhythms came through. But it's a bit difficult to explain to your mother-in-law what you're doing in her kitchen at four in the morning with a bucket and no pants on.'
And so it was that Heath invented what he calls - in honour of the original track suit - his Nikephone. When the piece is premiered this evening by the BT Scottish Ensemble, the audience will be required to be particularly attentive as percussionist Kirk Robinson pulls a track suit from a large vat of water and hangs it on a grille. The music of the ensuing drips will eventually be picked up and echoed by pizzicato strings - and once again a random element in the creative process will have produced the right results.
As a composer, Heath may not find all his solutions by such methods, but he is always open to unexpected possibilities. 'I set out a framework for what I'm going to do, then I fiddle around to find out which bits are going to go where. I find it's like improvisation. I think, 'That sounds great, that could go there.' There is intellect involved, but that's not my starting-point. Perhaps it's because I started as a flute-player. You begin by playing other people's music. As you progress you get a clearer idea of how you want to play, you want to control more things. It seems perfectly logical that you should end up wanting to write music. For me, a composer has to go out there and play to get a feel of what's going on.'
It is only relatively recently that the roles of performer and composer have become separate. Heath has tried several approaches to reuniting the two. Last year, the Minnesota Orchestra premiered his concerto Alone at the Frontier, in which the solo part was entirely improvised by Nigel Kennedy - in different ways on three consecutive nights. Heath's sense of how these two elements of music-making might be brought back together derives less from classical models than from the jazz improvisers. Heath's compass points are Charlie Parker, Miles Davis, Eric Dolphy: 'John Coltrane revolutionised basic tonal harmony. If you don't know what Coltrane did, to my mind you don't really know about 20th-century music. Classical music is off at a tangent: Schoenberg is an interesting sideline that people had to go down, it's not the main thrust. I think what will emerge as the true line of 20th-century music will be people who take the harmony of, say, Chick Corea and Herbie Hancock and turn it into contemporary classical pieces. But I'm not trying to be a jazz musician. I love orchestral music, that's what I do.'
So it is that Heath has taken up the post of composer-in-residence with the BT Scottish Ensemble. Under the terms of the residency (funded by BT), Heath will provide the Ensemble with two major pieces a year - The Four Elements is the first - and a number of shorter works that will function as encores. Heath has worked with the Ensemble before - he was the soloist when it premiered his second flute concerto, The Connemara, at the 1992 Edinburgh Festival; and he played in its Virgin recording of the fifth Bach Brandenburg Concerto.
Heath looks forward to confronting the possibilities offered by regular contact with the 11 string players who make up the group: 'It's a very good band, very exciting, and I have to develop a relationship that pushes them and that pushes me as well. It always helps when you know the musicians. They come to know the way I write and can say, 'Oh, that means this' - it gets a lot quicker. But they are not improvisers. I regard myself as the improviser, notating stuff for them.'
His next project with the BT Scottish Ensemble is to provide a violin concerto for its recently appointed artistic director, Clio Gould: 'I want to sit down and find out what she can do. Apparently there are some staggeringly difficult things she can do quite naturally, so I shall find out what they are and write to her strengths.'
The appointments of Heath as composer-in-residence, and of Gould as artistic director, are evidence of the Ensemble's attempts to move its music-making forward. Founded 25 years ago as the Scottish Baroque Ensemble, it decided to drop the 'Baroque' in the mid-Eighties because, says its managing director Roger Pollen, 'With the rise of the original instrument groups, to call yourself a Baroque ensemble implied a different style of presentation. And so much of the music which the group was doing was being commissioned, or was otherwise outside the Baroque period. Now the BT sponsorship gives us funding for Clio to put together concerts that are outside what we have built up a following for, in what are unusual venues - like the Glasgow Tramway - for a group like us.'
The Ensemble is a touring group because, says Pollen, 'The culture in Britain doesn't allow an orchestra like this to be anything other than a touring group. There isn't the local authority support to sustain the orchestra in a city.' For Gould, that is no disadvantage: 'It is quite new for me to able to play a programme again and again, in different venues. I'd never experienced the the way things evolve, how the personalities shift. Some nights you really have to work at it, other nights the contributions will be really strong. Because I direct from within the group, you get that eye contact which gives the audience a strong impression of what is going on, what is involved in making this music.'
Gould still pursues a solo career, but her commitment to the BT Scottish Ensemble is such that she has moved from London to Glasgow, which in turn has meant giving up her role in the Kreutzer Quartet. She has no regrets: 'I wasn't actively looking to leave London, but I like Glasgow, and the opportunity was so great. A touring lifestyle is very demanding. It's not compatible with family life, for example, it takes its toll, but it's great fun, and the audiences we get in Scotland are more personal than the average London audience.'
While she and her players are committed to unusual programmes that include more than mere tokens of the contemporary, she is aware of the problems involved: 'There's a danger of trying to be too clever. You can get a programme which looks fantastic on paper, but there may be all sorts of reasons why in performance it's not what you thought it would be - it's difficult to perform, or too bitty, or too long. We have a series in National Trust properties, and obviously one doesn't want to jar with the ambience. There are pieces which are too raw, too many emotions. If we're all charging away in the Bartok Divertimento in a small, resonant room, it wouldn't be a good experience for anybody.'
As Roger Pollen sees it, 'In classical music, the contemporary is the hardest to sell, but in pop, people want the latest precisely because it is new. There is no reason the two should be so diametrically opposed. Clio and I work closely together: she conceives the programmes, I've got to sell them. There is no point in me suggesting The Four Seasons and Eine kleine Nachtmusik at 65 venues on the trot, just because I know I can sell it; and there's no point in Clio doing all-Schnittke programmes. In that way Dave Heath is the perfect linchpin: the idea is to develop an understanding of his music in our audience over an extended period. We tour to some quite remote places, and you really get through to your audiences. They're quite discerning, they tell you exactly what they think.'