ARRANGING DEBUSSY'S PRELUDES FOR ORCHESTRA

The idea of arranging all 24 of Debussy's Preludes for orchestra came about almost by accident.

For the opening of the Hallé's 2001 season, which coincided with my appointment as Associate Composer, Mark Elder asked me if I had written anything appropriate to stand at the beginning of the concert. When he told me that the following music would be Strauss's Four Last Songs I wasn't so keen on anything of mine preceding such a masterwork, and so we talked about possible alternatives. The idea that emerged, of orchestrating some of the piano Preludes - which I have known and loved for as long as I can remember - was very appealing. At that stage, though, there was no thought that this might be other than a one-off experiment.

Nevertheless the thought of doing more was at the back of my mind, and so I deliberately chose to work on two of the most brilliant display pieces for the piano - Ce qu'a vu le vent d'Ouest and Feux d'artifice - knowing that if I could find a way to transcribe them, then others would certainly be possible. My procedure with these, as with most of the subsequent Preludes, was to try to think of them in such orchestral terms that anybody faced with my score would find it very difficult to turn them back into something resembling the piano originals. Not that I was in any way being unfaithful to the originals : but I wanted to orchestrate them on my own terms, not as if I was trying to create a pastiche of Debussy's own orchestration.

Inevitably - such is the strength of the musical ideas, and of Debussy's unique harmonic world - they sound very like Debussy. But from the beginning I felt that I needed to make compositional changes - mainly on the small scale - in order to make the music work on the much larger canvas of the orchestra. Most of these modifications, unless you know the originals very well, are fairly unobtrusive; but I did get more adventurous as I went on, and added a substantial extra section to Le vent dans la plaine, as well as completely altering the character of La fille aux cheveux de lin - the prelude that everyone knows! - by slowing it down to half speed.

What are the main challenges? The subtlety of Debussy's†piano writing, depending on half shades and scrupulous use of the pedals, is not always easy to render in orchestral terms, and parallels have to be found for the way that the sustaining pedal can blur the harmony, as well as for the natural decay of the piano sound. Several of the Preludes have had to be shifted to a different key - in the case of Les sons et les parfums there is no orchestral instrument capapable of playing the low A that concludes the piece; in La Puerta del Vino the rhythmic ostinato could only be played in one section of the piece by the cellos - as it needed to be - if I shifted the music from D flat major to E flat major, thus also making it sound brighter.

This recording of twelve of the Preludes has not followed Debussy's ordering into two books. This is partly because I haven't been working on them in order, choosing instead to put groups of three or four together that I felt would work well. But it also reflects the fact that in two cases I have joined separate Preludes - in this collection Le vent dans le plaine and La fille aux cheveux de lin play without a break; in the second set of twelve it will be Les fées sont d'exquises danseuses and Des pas sur la neige. They can, though, be pulled apart; and anyone who wishes to perform them in the correct order, or another order altogether, is perfectly free to do so!

It has been an extraordinary journey, entering another composer's mind in a way which has had, I think, a profound effect on my own music. It seemed only natural, then, to write a Postlude in homage and celebration, which I did immediately after finishing the final Prelude (La cathedrale engloutie). My own M. Croche (the name of Debussy's journalistic alter ego) written as a piano piece and then orchestrated, will conclude the final set of 5 Preludes which the Hallé and Mark Elder will perform for the first time in May 2007.

Colin Matthews