Have you heard the one about the oriental fantasy?

The Booker shortlist, announced this week is, in many ways, nothing but the same old story, the one about the Irishman, the Indian and the Antipodean, who seem perennially to be among the favoured few. So this year the likes of Roddy Doyle, Salman Rushdie and David Malouf step aside for fresh ranks of compatriots, namely Bernard MacLaverty, Arundhati Roy and Madeleine St John. The space for the required up-and-coming first novelist is filled by Mick Jackson. And there are a couple of places for solid writers with a track record, Jim Crace and Tim Parks, who - on the Buggins' turn principle - deserve a little of the limelight. In short, there is nothing revolutionary about this year's Booker judges.

Yet the choices are refreshing at least in ignoring much of the hype in the book trade about authors deemed a cert for the list. The fact that two out of the five judges - Jan Dalley and Jason Cowley - are long-standing literary journalists, means that the panel will have taken a jaundiced view of being bounced into certain choices by the books trade.

One casualty of this scepticism was John Banville, the Irish writer, whose fictionalised story, The Untouchable, based on the life of Anthony Blunt, was bought by Picador for an exorbitant fee and pushed relentlessly by them as a natural for the Booker. The talking-up of Ian McEwan's Enduring Love may also have backfired. It's generally regarded to be a much better book that most published this year, but it is McEwan-by-numbers, running through many of his old riffs. The Booker jury, which includes two senior academics, Gillian Beer (who chairs the jury) and Dan Jacobson, is sufficiently well-read to be familiar with the previous work of well-known authors. The days when a gullible celebrity, with little literary background, was recruited on to the panel to catch the public eye are long gone.

Not that the panel wants to seem too elitist. The choice of Madeleine St John's The Essence of the Thing is not only a huge surprise. It is also a nod in the direction of popular fiction, a genre which previous juries have stoically ignored. The novel dips into a world that would be familiar to Bridget Jones - of life in west London's Notting Hill and the aftermath of the break-up of a relationship. It centres on the life of Nicola, who is trying to put her life back together after the departure of her lover, Jonathan. The book is hardly ground-breaking in its ambitions and has been panned by some critics as cliched. Its theme and location have, after all, preoccupied writers ranging from Muriel Spark in the Fifties through to Anita Brookner in the Seventies and Eighties.

It is perhaps forgivable that this book should have displaced Jeanette Winterson's widely tipped Gut Symmetries. Winterson breaks so many rules of conventional fiction and is so idiosyncratic in her style that she divides readers sharply between those who love and those who loathe her work. But it is harder to understand how Madeleine St John's ordinariness could have elbowed aside Carol Shields, a first-rate novelist, whose latest work, Larry's Party, has as its central character a forty-something man who is trying to making sense of his life. It demonstrates that Shields, always known for her skill in creating heroines, is just as adept with her heroes.

In one respect, however, the judges have made an indisputably sound choice. The God of Small Things by Arundhati Roy, has, it is true, been hyped at least as much as the output of John Banville and Ian McEwan. Since last year's Frankfurt Book Fair, the manuscript has heralded, amid a great buzz about the discovery of an unknown Indian genius. In this case, the fuss has been well-founded and been sustained through the ensuing months.

Arundhati Roy, though from a professional background, had until this book no experience of writing and publishing fiction. Her novel was an act of faith. When she wrote it, she gave up working in the film industry to write a book that had no obvious prospects. Yet the novel reveals that this writer, on her debut, has a fully-fledged style and vision. It has the flaws of a first novel, being in places over-written by an author in love with her own stylistic virtuosity. But it remains deeply moving.

The God of Small Things is also unlike the classic Indian novel in English, which typically appeals to Anglo-Saxon fantasy about an exotic land. Roy has set the novel in the lush landscape of Kerala in south-west India, but she does not pander to traditional orientalism in the way she presents Indian society. There is a distinctive autobiographical tone as she looks at the Syrian Christian community in which she grew up. The story is of a tragic marriage to a Hindu man of low caste outside that community. And so it reflects how her society is racked by conflicts between the energy of modernity and the demands of existing tradition. As the plot unfolds you see these issues played out against a very real, up to date world of bill boards, radio jingles and pop music.

If this week's shortlist reflects any key principle it is that which awarded Salman Rushdie the Booker with Midnight's Children in 1981, namely that the Booker Prize should be a major showcase for the varieties of English language fiction both within and beyond the British Isles, and not simply in the old metropolitan centres. This attitude acknowledges that the future of the English language is being forged in the Glaswegian dialect of James Kelman's 1994 winner, How Late It Was, How Late and among the Dubliners in Roddy Doyle's Paddy Clarke Ha Ha Ha (the 1993 winner).

Experimentation with language can be found in Jim Crace's shortlisted Quarantine, which dramatises Jesus's 40 days and nights in the wilderness and attempts to create a language appropriate for first century Judea, without producing a pastiche of the authorised version. Likewise, in The Underground Man, Mick Jackson attempts to get inside the head of an eccentric and possibly demented aristocrat.

Thus, like many Booker shortlists, there is a sense of standard literary English being pulled in many different directions both historically and geographically. But the process of refining and renewing English is most innovative in Arundhati Roy's first novel, which is why this extraordinary writer deserves to win the plaudits and the pounds 20,000 when the judges make their final decision next month.