The rhythms of the deep

The earliest music was motivated by rhythm, by the tapping of stone and wood, by clapping and shouting. The tides move through our literal days and nights with calculable precision and affect our dreaming nights too, for the sea is perhaps the oldest and most potent symbol for the unconscious as both poets and psychologists remind us. Seawater is quite like human plasma in structure, and there is even a hard-science theory, post-Darwinian, that we come from the sea and, hence, yearn for it.

This year the sea provides a focal point for the BBC proms that include the Overture to Wagner's The Flying Dutchman (29 August) as well as the whole of Die Walküre (18 July). For me the Ring Cycle, and indeed just about everything that Wagner ever wrote, is ineluctably connected to the ebb and flow of water.

Also present, of course, is that pre-eminent depiction of the sea in all its myriad moods, La Mer (9 September). In order to experience at first hand the vagaries of the ocean, Debussy (who was much influenced by Wagner and, in particular, Tristan) took a storm-tossed boat-ride and found, in his terror, an exhilaration that resonates wonderfully in the ebb and flow of the music that it inspired. Since he had just left his wife for his mistress, it is tempting to read into the music a personal turbulence, but Debussy is a composer of such subtlety that he defies facile psychoanalysis. Indeed, he hated the easy pigeonholing of his art with that of the Impressionists, pointing instead to the more vigorous influence of Turner and his wild depiction of light and storm. There is another connection with England because, rather improbably, given its delicious Frenchness, Debussy took a suite of rooms at Eastbourne to correct the proofs of La Mer.

The score resembles, graphically and more than any other I know, wave upon wave, rising and falling; it smells of the sea. For the cover of the first edition, Debussy specifically asked for the exquisite depiction of a breaking wave by Hokusai, thus reflecting another profound influence, that of the Orient, of pentatonic scales and gamelan.

Unlike Debussy, Britten's personality traits seem rather more boldly manifest, both in his scores and in his choice of subjects. It is hard not to feel in the music something of the inner struggle in the man. Despite his humanitarian and pacifist beliefs, Britten had rather conventional, not to say conservative, views, so discovering his own sexual preferences at a time when homosexuality was illegal was probably disturbing. Not so WH Auden, a wise old bird from birth it would seem, who recognised that "young Benjy's" lack of security and independence might well lead him to fall prey to an adoring court.

Like many prodigiously gifted and acclaimed young people, Britten seemed locked into a form of youthful adolescence in terms of his social dealings. In the certainty of his gifts he perhaps missed out on some of the emotional rough and tumble that most of us experience. As a result, he remained wedded to what he knew from childhood - schoolboy fare and self-discipline. Rice pudding and spotted dick were the order of the day, with bracing swims in the North Sea all year round. Having just shivered my way into the Aldeburgh lido in the middle of a heat wave, I can well understand the need for wholesome sustenance, spotted or not.

Britten's Four Sea Interludes (5 September) from his opera, Peter Grimes, capture brilliantly both the huge thrashing waves of a big storm and the glittering calm of the sun playing on placidly deceptive water. This opera, as with several of the others, concerns itself with the corruption or destruction of innocence, and a protagonist wrestling to control his inner demons. In its very unpredictability the sea appears to mirror Grimes's moods; "Grimes is at his exercise," sing the chorus and, as Billy Budd is destroyed by Claggart, and Miles corrupted by Peter Quint; so, we might ask, is Britten too at his exercise - or should that be, perhaps, "exorcise"?

A great deal of my childhood was spent on the north Norfolk coast, and the best job I ever had was working as a teenage boatman, ferrying bird- and seal-watchers from the creek at Morston across the estuary known as "the pit" to Blakeney Point. Since there would also be many families with small children, and a desire for picnics, this was a job of some responsibility for someone so young - you needed to know the channels and you had to impart a certain confidence in the roughest weather. Britten, a lifelong friend of my father, would sometimes take the opportunity to put his sports car through its paces (yes, ever the boy racer!) and, with Peter Pears, join us for a picnic on the point. As an extraordinarily conscientious godfather he would send me postcards from wherever he and Peter were performing, and would encourage me to send examples of my juvenile compositions. These he would read with a kindly but professional eye, and return with constructive and encouraging comments. One, in fact, was called Morston Marsh, and attempted to describe the desolate salt marshes in the pallid light of an East Anglian winter. Given Britten's precocity, I cringe now when I think of the few serviceable bars in the piece.

Reading through a draft of an illuminating new book by Tony Scotland about my father, Lennox, and his circle (Britten, of course, but also Auden, Ravel, Poulenc and the Stravinsky household), I began to realise just how much the brine is in the blood. Lennox's father, Hastings, was a captain in the navy; his uncle Randal, Earl of Berkeley, was a naval officer before inheriting Berkeley Castle, and his great-great-grandfather, Admiral Sir George Cranfield Berkeley, was a young lieutenant on the Victory at the Battle of Ushant in 1798. Lennox himself might have followed his father into the Navy if he hadn't been disqualified by colour-blindness. As it was, the closest he got to a battleship was writing an opera on Nelson and inspecting the waters of Trafalgar from an aircraft carrier fitted out with two grand pianos so that he could play Mozart and Schubert with his friend the flag officer, Admiral Lamb.

There is a very different feel to life on the ocean and our perception of it from the land. But, even if the immensity of it is diminished, I still experience a childish thrill when arriving at the sea and getting that first glimpse of an endless horizon; inevitably I hear in my mind's ear the overwhelming opening to the Vaughan Williams Sea Symphony: "Behold, the sea," with its attendant, mountainous chords (23 July).

In the very first week of this year's proms there are two new works with maritime links, both of them dramatic. Thea Musgrave's Turbulent Landscapes shares at least one connection with Debussy's La Mer in that it, too, is influenced by the seascapes of Turner, who, like Debussy, was so committed to his art that, in the most dramatic seas, he had himself strapped to the mast in order to study, with impunity, the effects of light on water. Turbulent Landscapes receives its first London performance on Wednesday 20 July by the orchestra that premiered it, the BBC Scottish Symphony Orchestra, conducted by Osmo Vanska.

The previous evening, the BBC National Orchestra of Wales, give the world premiere of my Concerto for Orchestra, which is dedicated to the orchestra's principal conductor, and my long-term collaborator, Richard Hickox. This is the second work I have written for the orchestra since I was appointed their Composer in Association.

One of the great advantages of an arrangement like this is that you get to know the individual strengths of the players and they, in turn, become familiar with your musical language. A concerto for orchestra seemed an ideal vehicle to reflect this relationship, and it follows Tristessa, a tone-poem which featured the principal viola and the then cor anglais player. During the rehearsals for that piece I had several conversations with the orchestra's brilliant first trumpet, Philippe Schartz, who asked if I might consider writing a piece featuring his instrument. This is the kind of feedback composers relish and it gave me the idea that, rather than write an entire trumpet concerto, I might do a piece with a central movement led by a solo trumpet. It had been my use of mutes that had intrigued Schartz, but, in the final analysis, the slow movement relies purely on the natural beauty of the open bore of the trumpet when played with great control.

I began, however, with the first movement and a very simple idea; falling tones as in "Three Blind Mice"! At that point I sketched out a rough architecture for the piece; a fast-slow-fast pattern in which the first two movements would have the falling tones and the last would invert them into a rising pattern. It also struck me that a further symmetrical touch would be to have both the outer movements themselves set in a fast-slow-fast design. Of course the music hardly sounds like "Three Blind Mice", but the reason for such an elemental theme came about through reflecting that it is not the idea itself that matters but how you develop it.

By extending this motif to a fourth whole tone I found my second subject, a motif which also played a big role in my first opera, Baa Baa Black Sheep.

Perhaps the most famous concerto for orchestra is the one that I studied for O-level, the Bartók. Strangely, though, I have always felt that it is less a virtuoso piece for orchestra than those earlier, scintillating, masterpieces, The Miraculous Mandarin and Bluebeard's Castle. The concerto, written at the very end of Bartók's life, is more a consolidation of his technical and orchestral prowess and it is almost as if the composer is slightly sitting back and enjoying himself. The result is music of great argument, charm and easy access but, even here, Bartók has a surprise. Although he calls it a concerto, it is of symphonic proportions, with five movements.

Despite my admiration for this piece the only real connection is possibly the fact that my own work is not as expressionistic as, say, my Clarinet Concerto. Both the outer movements begin with an almost scherzo-like call to attention and both become increasingly serious as the music unfolds, so that, by the time we reach the closing bars of the opening movement, we seem to have entered a darker landscape. This sets the tone for the slow movement, which begins with muted and divided strings descending. Two piccolos punctuate the thin wash and herald the lament of the solo trumpet.

It was while I was writing this music that the dreadful news of the Asian tsunami began to break. We all tend to deal with global disasters in a manner that, while shocked, is somehow dissociated. This was brought home to me when I learned, a few days later, that someone I knew personally, Jane Attenborough, had perished, alongside all the thousands who were nameless to me, with her daughter and mother-in-law. Being able to fit a face and personality to one of the victims for me brought the tragedy into another dimension.

I first met Jane through her work with the Paul Hamlyn Foundation, which takes the arts to a wide cross-section of society. So it seemed to me that it might be fitting to dedicate this movement as an In Memoriam to Jane. And, certainly, the second half of the movement was informed by this more personal response to a larger and less easily encompassable tragedy. The music is grief-stricken; but it has, too, I hope, an air of hesitant tranquillity which suggests some possible element of acceptance and repose.

The mood is dramatically broken with splashy Chinese cymbals triggering an inversion of the opening music, and a frantic scurrying towards the sky. But the onward rush of sound is soon brought to book by the emergence of the trumpet melody from the slow movement, and then there begins a synthesis of all that has passed.

Although the music is not in a specific key, there are shifting tonal centres, rather as in the sea, where you find constantly moving sandbanks. Indeed, the more I look back at the music, the more I now see it as having many of the qualities of a score that was overtly inspired by the sea; the way something playful can become something menacing. The notes that we hear in the first few bars, for instance, suggest a raucous, vaguely A-major, feel. But, by the end of the work, the same notes are now part of the more disturbing sound-world of C sharp minor, as though storm-clouds have now appeared on the horizon, and there is that sense of damp menace.

Seeing visual or programmatic connections after the music has been written takes us back to Debussy who often attached, after the event, utterly apt and natural titles to his highly descriptive piano music. This gives rise to the idea that if water, for instance, had not been thought of consciously as an inspiration, it had, in fact, been subliminally present all the time as an underlying and unconscious motivating force.

Michael Berkeley's Concerto for Orchestra is given its world premiere at the BBC Proms on Tuesday 19 July, and is broadcast live on BBC Radio 3 and BBC Four. The Proms open tonight at the Royal Albert Hall. (020-7589 8212; www.bbc.co.uk/proms.