The third symphony is the big one. Weighing in at almost eighty minutes, it is at the limits of a single orchestral work in stamina terms alone.It was the first thing I wrote with a decent score editor, one that didn't crash if the file got too big, and so the scale was an articulation of liberation. Having decided on large, I had to consider the same stretch of structural considerations as say, Bruckner or Mahler: the application of self-doubt inherent in the arts of the possible, as opposed to the arts of the marketable. Structural form, as the words suggest, is the frame on which everything else hangs, and if everything else is too heavy, the structure collapses. Wagner used this as an excuse for interminable mush filled with interrupted cadences that didn't lead anywhere; forsaking structural architecture for a tediously knitted fabric with all the delicate pre-planning of a soap opera. I wanted to see what in the old architecture could be saved: in other words I wanted to give symphonic form an extra couple of bedrooms and a loft conversion, to make it more grandiose in scale without sacrificing the whole house.

All this was only vaguely in my mind at first. Symphonies can't be written in an afternoon, or even a dozen afternoons, of course, and if you only focus on the whole then you run the risk of crumbling under the weight of your own ambition. I picked a more modest target to start with: 1000 bars. I figured that if I could write a thousand bars of continuous music of decipherable structure then I was a good part of the way there. The problem of whether grand architecture, or the notion of musical architecture at all, was by now a mute concept, must be seen in the cold light. Since Webern, the prime focus has been on economy, not grandiose cathedrals; and the musical economists hold that a beautifully arched melody is redundant when one squawky note cluster will do. i'm not arguing for retrograde action- I am no neo-classicist. I just believe bath-water is of a little less value than a baby, even in these days of metered water. The reaction against classicist norms was, 50 years ago, so sweeping that figures as huge as Shostakovich and Britten had reputations as 'passé' before they even reached maturity. But here the rift was forged. Concert audiences, subject to the whims of a few pseudo-intellectualist composers, sat passively through the latest higher math of Boulez, or the latest coy piss-take from John Cage, and; as they thronged to the blessed bar afterwards like John Mills and the gang in 'Ice-Cold in Alex', they dreamt of some olden golden time when a concert involved active enjoyment of the music. By the time I was receiving, or rather self-creating, a structured musical education, the mighty camp of neo-serialists, polytonalists, atonalists, aleatorists and just plain give-you-a-headache-ists were so much the establishment that concert-goers lost any sense of a cultural continuum, any regard for the historical place of the present. The rift I allude to, grew to a chasm between the concert composers with their equations and theories, and the mainstream of the new popular music, which, by no accident, served up sugary melodies and simplified rhythms and pleasant textures and basic forms and made itself into an industry with about as much clout as the Roman Empire. There was even room for Tchaikovsky or even Prokoffiev or even a 'modern' like Bernstein if he behaved and wrote big band music. And now, in these dark ages of market forces and death to the minority, the concert music scene has been subsumed by 'pop classics' served up with South Bank cocktails at a fiver a pop. We can blame the atonalists for doing too little to respect their audiences. We can blame global capitalism for its relentless MOR cultural genocide. We can blame Sir Peter Maxwell Davies for writing some real crap. Still, the rift leaves only one choice for any composer unlucky enough to be trapped in this time: you either embrace the latest 'modernism', safe in the knowledge that nothing you write will leave your bottom drawer for forseeable decades, or you hawk your arse with as much enthusiasm as you can muster to the film industry, the advertising industry, and twiddle about with tv themes for the rest of your just about feasibly prosperous life.

Bliar used to blie about his 'third way'. Like everything else he said in his sorry little career, it meant different things depending on whether you were looking for reassuringly left-wing rhetoric of the sort that makes you vote Labour; and the reassuringly right-wing practise that makes those truly in power tolerate Labour. In reality, though, the third way meant: say one thing; do another; and then lie about it being something else entirely. It was thus pluralism went the same way as socialism: dropped in the bijou waste-disposer by Mrs Bliar's cook. So it is left to musicians, of all people, to fight the conceptual fight and re-engage with such currently out of vogue pastimes as rational discourse, cultural relevance, or indeed plain old intellectual thought.

My third symphony looks (and sounds) different dependent on the aesthetic perspective you choose. It is traditionalist in certain aspects: its use of tonality and almost classicist architecture. It is modernist, or at least of the 20th century, in mood, texture and construction. It also follows a narrative, a contemporary narrative in essence a structuralism: the grand scale necessary for its global and societal context; a big philosophy for a big conceptual ideal. The subject is the planet we live on, and the world we live in. The first movement traces our path from the primaeval swamp. I try to depict our huge rotating planet, the strings of life-giving molecules, and in an extended central crescendo section and the following slow accelerando, the onward march of nature, evolving across time. The second movement is classicist, architectural, the philosophy of the timid beginnings of civilisation. The third movement evokes our increasingly complex societies in one giant overblown scherzo. People by the million, working, toiling. The growth of the collective will. The finale is a case study in collective endeavour, an optimistic philosophy of the many of humankind. The two main subjects co-habit, free from conflict, in that blazing light of the future so out of fashion at this time.

If you look at our planet, the dangers and the suffering, it is easy to be pessimistic about our future. Even when you're allowed a stable grip on reality despite all the distraction and deception, you are bowled over by dark, nightmare scenarios; foretales of whatever apocalypse fits your hat-size, from land, sea or air.And yet so many thinkers propose the rather comforting idea that whatever kills us all, fire, ice or radiation, our home, our planet Earth will survive, and eventually thrive without our destructive infestation to host a superior species better blessed with moderation. If this is far-fetched as optimism, it is one of the few optimistic concepts that isn't undermined by grim real life.

Of course we have one sure cure for all our possible futures: mutual co-operation. If our history tells us anything, it's that humanity constantly creates divisive conflict; never once has mankind acted with a common will. This god, that god; this economic system, that political ideology. What seems self-evident to the averagely bright six-year old, replacing the world of playground punch-ups with a world of equal shares, is beyond the nouse of the Macchiavellis who ruled any age. They point to the mob rule of Stalin and the purges of Mao-Tse Tung and tell us egalitarian societies will always come a cropper, that greed and exploitation is somehow a fairer way to live. We have to accept that greed and exploitation seem to be first nature to us; that our ancestors, the blood-thirsty beasts who climbed to the top of the food chain in the first place, left us a legacy in which kicking him for staring at your 'bird' is perhaps our basic 'natural' behaviour. But on every scale larger than the taxi-queue outside 'The Ritzy' in a town centre near you, we expect to find reasonable men: even the men. Reasonable people seek agreement, compromise, a proportionate sense of wants and needs, crimes and greeds. We are not ruled by reasonable men. All the major players in our one shared future base their flawed prospectuses on the flawed gods of the Holy Roman Empire- Jesus H Christ and his backing-group, the original gospel singers. Not the egalitarian alternative theology of Jesus the Jewish rebel and proto-Communist neither. But a white-skinned Jesus offering to cure homosexuals of being gay, offering to turn ganja-smokers into economically productive out-patients, and above all, offering to have it out with Mahommed, blessed be his something or other, over which particular suburb of heaven we all get to live in after we've killed each other. But this is a dark age, and our grandchildren will see the lunacy for what it is, as our children already do.

My third symphony is about the joy humanity will find one day; about a planet we seem rarely blessed with in the vacuum of space. It is filled with symbolism, realisations of conceptual space: themes that merge into one; subjects that compliment rather than conflict. It is a big piece, some would say fat. But i'm a fan of fat books. The weight of intellectual creation is as nothing to the satisfaction of work achieved, especially when you've finished something with barely any outside help at all. And yet music writes itself, in a philosophical as well as a practical sense; so i'm better off not feeling too smug just yet.