In his epic poem Omeros, a retelling of the Odyssey in a Caribbean setting, Derek Walcott imagined that his father was named "in love or bitter benediction / ... for Warwick. / The Bard's county". Warwick Walcott, the offspring of a white plantation-owner from Barbados, was a cultured man who painted, wrote poetry and organised theatrical evenings on the neighbouring island of St Lucia, where he had settled with his family. He died at the age of 34, when his son was just over a year old, on April 23, Shakespeare's birthday.

Autobiographical motifs in Walcott's poems are frequently stitched together with literary reference: Buck Mulligan, Dante, TS Eliot, Wilfred Owen, among others, crowd into a single poem written when he was in his teens ("Epitaph for the Young"). Over them all, the shade of Shakespeare hovers:

So I began to write, to take up

arms,

Fitting out vaguely for a pitiless

sea,

Willing to drown under impersonal

stars ...

Derek Walcott was born in 1930 and raised on St Lucia, one of the smaller Windward Islands of the Caribbean, where he received what he calls "a very good English education". His generation, as much as his father's, "treated the English texts as if they belonged to us, because English is our native tongue". In response to the postcolonial agitation which all but insists that an artist deploy his art to strike back against ex-imperial masters, he has maintained a sometimes mild, occasionally fierce, always super-articulate independence of mind. "It is the [English] language which is the empire," he has written, "and great poets are not its vassals but its princes."

Once the literary impulse had been aroused by the mingled atmospheres of home and school, Walcott's reaction to it "was the very same as an English schoolboy who wanted to be a poet would have: to take models that were in literature - Auden, MacNeice, Dylan Thomas - and make them your own. They were immediately accessible, with no feeling of alienation about it - 'Oh, wait a minute, I shouldn't be reading Thomas! Welsh!'" His mother Alix, a light-skinned woman from the island of St Maarten, who is still referred to by familiars as Teacher Alix, nurtured her uncommonly gifted son's ambition. "My first book of poems was published privately in 1949," Walcott recalls, smiling. "That was my mother. The book was 25 Poems. It cost 200 dollars."

Walcott is in exceptionally good condition for a man of 78. On his stocky, well-toned figure an outfit of baggy linen trousers and black T-shirt bears no trace of youthful affectation. A heavy smoker for much of his life, he banished tobacco and alcohol a decade or more ago. He speaks with a Caribbean lilt that frequently hits distinctly melodious notes: "Shake-speare"; "dia-logue".

There was scant room for an artistic community on St Lucia - "the steamers which divide horizons prove / Us lost; / Found only / In tourist booklets" - and in his mid-20s, Walcott moved to Trinidad, the largest island of the region, in search of more fertile ground. A few years before, VS Naipaul had sailed to England, scornful of a cultural desert left behind. The two men were once friends, but lately have turned publicly antagonistic. The most recent aggravation came from the disobliging account Naipaul gave of Walcott's emergence on to the literary scene in his memoir A Writer's People, published last year. Walcott responded with a recitation at a poetry festival in Jamaica in May, when he read a "nasty" poem called "The Mongoose". It began: "I have been bitten. I must avoid infection, / Or else I'll be as dead as Naipaul's fiction." Friends who recall that Walcott once spoke highly of Naipaul's achievement now caution that the name be left unmentioned in his hearing. Unprompted, Walcott offers it himself in a slip of the tongue when discussing the Nobel prize: "Look at the people who never got it: Auden, Frost, Naipaul - I mean Nabokov ..." (Naipaul received his in 2001, nine years after Walcott.)

In Port of Spain in 1956, Walcott took a job as a reporter on the Trinidad Guardian (where Naipaul's father had worked), covering local news and school art exhibitions. At the same time, he was writing and directing for various theatre companies.

Theatre is the leeward aspect of Walcott's literary career. While his life as a poet presents, in the words of the American critic Adam Kirsch, "an almost uninterrupted progress in mastery", his 80 or more plays have remained largely local. The view of him as a man of the theatre is obscured only if the viewer happens to be looking from New York or London - what Walcott, with a touch of well-worn impatience, calls "the centre of cultures. This is a thing that we face often. 'Is this the first time you have done a play? ... Is it a debut? ...' I have had a lot of premieres, in the Caribbean. Then they have moved elsewhere."

He is referring to the forthcoming production of the opera The Burial at Thebes. This particular premiere is being mounted in London, at the Globe, and according to publicity released by the musical company that commissioned it, Manning Camerata, it is "Walcott's first experience of directing an opera". The libretto is based on Seamus Heaney's version of Antigone by Sophocles, with music by the Trinidadian composer Dominique Le Gendre. Preliminary discussions about set design and other matters took place in the summer in Milan, where Walcott was the guest of an arts festival (an outsider might imagine his life to be one continuous, nation-to-nation commute).

Negotiations over casting were facilitated by computer wizardry, adding to his natural apprehension. "It's quite terrifying for me," he said, as rehearsals were due to begin, "because I keep thinking of it as a play. I have to adjust. It will be shocking to realise that it's not a play - it's people singing."

Le Gendre has barely adapted Heaney's text. "The whole point for me was to use the text in its entirety," she says, "because it utters its own music. I have tweaked the odd word here and there, that's all." She is making use of Trinidadian "rapso", which combines "calypso musical riffs, social commentary and rap. The most important element is the lyrics. Like rap and calypso, rapso provides a rhythmic, declamatory comment on any given situation." In St Lucia a few years ago, Walcott organised the staging of some scenes from The Burial at Thebes, in Heaney's presence, using local actors. "Not as an opera, but as a play," he says. "So I know the feel of it, and I think I have an idea of what he intended."

Antigone is the story of a woman forced to choose between loyalty to family and to state, when she insists on burying her brother, whose corpse has been left to rot as that of a traitor by King Creon. Antigone is condemned to death - "The right observance put me in the wrong," she states - and a last-minute change of mind by Creon, on the urging of the blind seer Tiresias, comes too late to prevent her taking her own life. Fate, as predicted, lands Creon with a hefty bill.

"I always have difficulty with the Greek tragic plays," Walcott says. "I think the difficulty one has - which is a serious problem - is the question of belief. Do you believe in the myth that the play expresses? Do you believe in it as myth or as reality? With any play, you have to believe in it as reality. You can't act a myth." His intention is to focus the audience's attention on character and language. "It depends on the poet every time. He can make his language grandiose, but the interior tone must be human. That's the achievement of Shakespeare: this grandiose poetry is spoken as if somebody could say it. As if we could talk like Macbeth."

Heaney's version is written in standard English with an Irish accent. While retaining the Theban scenario, he uses a down-home idiom, with phrases like "cock-of-the-walk" and "the likes of us". The reader need only compare Antigone's opening words in the Heaney version with those of RC Jebb (1904) to see how ancient classics offer base metal for transformation. Jebb's Antigone says: "Ismene, sister, mine own dear sister, knowest thou what ill there is? Knowest thou aught? Or is it hidden from thee?" In treating the same lines, Heaney conveys the gist, while registering a familiar tone: "Ismene, quick, come here! / What's to become of us? / Why are we always the ones?"

For the opera, Walcott has changed the tone again. Whereas Heaney kept the action in Thebes, Walcott moves it to a modern Latin American republic. Creon has cast off his robes and donned a shiny, sharp suit. The idea was sparked by a visit to the Dominican Republic, which was ruled for 30 years, until his assassination in 1961, by the dictator Rafael Trujillo - according to most accounts the embodiment of cruelty and ruthless machismo. "I'm not changing Creon into Trujillo, but to me it's quite legitimate to take a play and treat it in a context which is closer to our experience. After all, that's exactly what Sophocles was doing. He was using an old legend anyway, and making it modern."

As a poet, Walcott stands in opposition to many of his contemporaries. Whereas the prevailing tone of modern poetry is idiomatic and conversational, he repeatedly returns to traditional forms, risking exotic flights in language (leaving him open to the charge of being airily rhetorical). Few of the younger Caribbean poets have aligned themselves with the Walcott manner; many prefer forms tailored to live performance - rap, dub, narrative. In the 1970s, Walcott came under attack from the Black Power movement on Trinidad, and later, on St Lucia, a group of performance poets staged a protest against his traditional loyalties - which are always in danger of being misread as "English" or "colonial" allegiance. When his name was mentioned in connection with the vacant post of Poet Laureate a decade ago, he did nothing to discount himself. On a visit to St Lucia in 2004, the New Yorker journalist Hilton Als observed that while the central square in Castries, the main town of St Lucia, was renamed Walcott Square after the Nobel award, local bookshops still failed to stock his books. (To date, Walcott has published more than a dozen collections of poetry, including The Castaway, The Star-Apple Kingdom, Another Life and Tiepolo's Hound, illustrated with his own paintings.) In the US, where he taught for many years before retiring recently from Boston University, Walcott was frequently accused of being not black enough. Bruce King, author of the biography Derek Walcott: A Caribbean Life, observes that while Walcott was "much in demand on the Black Studies circuit", he regarded cultural black separatism as "continuing segregation".

For his own part, Walcott dismisses the misconception of a white/black dichotomy in the Caribbean, preferring to stress the ethnic variety. "My generation produced some terrific writers, from all over, and the great thing about it is that they were all mixed in race." Harry Ross, the managing director of Manning Camerata, points out that "Derek was very keen that there not be an all-black cast for The Burial at Thebes".

Politics are liable to fuse into aesthetics in Walcott's conversation. His literary theory could be boiled down to a single principle: that the artist must make maximum use of the resources of tradition. "If you asked a young Caribbean painter, 'Why are you painting like Turner? He was an Englishman,' he would tell you fuck off. As writers we're not as belligerent about this as we should be. What is taught in schools generally in the West Indies is that if something is your thing, it's better than anybody else's because it's yours. It's extremely provincial, and also damaging. You prevent people from learning things. The biggest absurdity would be: 'Don't read Shakespeare because he was white.'"

His own experience in universities allowed him to witness "the terrible devastation to young minds caused by people who are poets themselves, who believe there are all sorts of horrible things about technique". As a teacher, Walcott insisted on "the importance of the shape that you make out of a poem. That makes me a dinosaur, an old fogey. And why should I care? I always cite something that Pasternak said: 'Great poets have no time to be original.'" Imitation, he believes, "is not only a form of flattery, but is in a way creation. No two things are going to be alike. Whatever you bring to the craft is going to be individualistic." Bruce King suggests that, because of his education, Walcott was raised "in the Arnoldian world, not the Third World". Walcott agrees, though it is Matthew Arnold "with a percussive beat".

The Burial at Thebes may be his first attempt at directing opera, but Walcott has no shortage of experience of writing and directing musicals. The Joker of Seville played throughout the Caribbean in the 1970s, but a Royal Shakespeare Company production collapsed on the eve of rehearsals in 1975 over problems with funding.

His most high-profile involvement in musical theatre is almost certainly the least happy: in 1998, the Broadway production of Paul Simon's The Capeman, directed by Mark Morris with libretto and book by Walcott, closed after two months. By that time, three directors had been fired and Walcott's lyrics had been dismantled and put back together by other parties. The Capeman told the real-life story of a Puerto Rican teenager who murdered two men and injured a third - "because we were white", according to the survivor, who must have hastened the show's demise by inquiring why "that should be anything to sing and dance about". Even here, Walcott was attacked on the basis of identity politics, with Puerto Rican writers wondering why Simon didn't choose one of them.

Walcott is eager to forge a link between the damage done by "bad teachers" who urge students to throw out poetic technique - "to beware of melody" - and what he calls "the totalitarian view of anything, the callous view, the indifference to beauty. If you are indifferent to that, as part of your politics, then everything is permissible. If you can say God is dead, then harmony is dead, melody is dead, music is dead, therefore faith is dead. Therefore it's easy to do what you have to do in the name of necessity. The rules no longer apply. You have something that is a semi-poem, just as you have something that is a semi-democracy or a semi-foreign policy. And you don't count the dead in Iraq because it's not part of the melody."

He is critical of contemporary American poets generally, for not addressing the topic of war. "America is so isolated from what is happening that poets still don't write about the foreign policy of their country. You don't get anything from them that says: 'We are doing terrible shit to the world.'" It is part of the reason why he wanted to do the opera, and why he is making King Creon the head of a modern state. "It's about civilised, high-toned tyranny."

When poetry is banished from the theatre, Walcott believes, the tragic genre itself is diminished. "What passes for poetry in the theatre now is lighting. Mood. The equivalent of tragedy, particularly in the American theatre, is really high-pitched nervous breakdown. Think of something like A Streetcar Named Desire - a clinical case. So it's great to have a poet like Seamus doing The Burial at Thebes. There is no reason why more poets should not be writing for the theatre. I've asked quite a few to do it. But they say, 'Well, I don't write plays.' I say, 'Well, you should.'"

The Guardian, Friday 3 October 2008