[In the following interview, Young attempts to define the forces that drive Pratchett to write within the fantasy genre.]

Terry Pratchett has finally achieved the status of a national institution as our foremost comic novelist. He is the literary equivalent of John Peel—similarly known as a lovely man. Modest, unpretentious, ironic, both he and Peel emanate a comfortable sort of mild subversion, like a favourite woolly jumper at a black-tie dinner.

It would be worse than uncharitable to mutter, like the mother in the Louis MacNeice poem presented with her fifth baby, ‘Take it away; I'm through with overproduction’. Yet, to the twisted soul of the bibliophile, it is never wholly easy to see a beloved author pass from cult status into mass cultural acceptance. Having feasted rapaciously and virtually in private, sometimes for years, on the work of writers such as Pratchett, Ruth Rendell, Don DeLillo or Alice Munro, the pleasure one feels when they are finally accorded their well-earned acclaim is always tempered by a faint sense of loss. Ungraciously, the bibliophile starts seeking another gifted unknown to collect. But then bibliophilia is a pathological condition marked by covetousness, elitism and other undesirable, seriously psychopathic traits.

Carpe Jugulum is the second Discworld novel to come out this year, and the 23rd book in the best-selling series. A lengthy canon such as comprises the Discworld novels has so many loyal and indiscriminating fans that it seems almost superfluous to assess each novel separately. (Who, apart from obsessives, can differentiate between the Jeeves books?) Suffice it to say that any such cycle has its ups and downs and that the last really great Discworld novel was Hogfather. Carpe Jugulum is far less animated and memorable.

For anyone who has spent the last few years in religious retreat or a chemical stupor, Pratchett's great creation is the Disc, ‘world and mirror of worlds’, a flat earth carried through the endless starry reaches of space on the back of a giant turtle. Sea pours endlessly over the rim of the Disc and at its icy centre is The Hub, where the gods live in a place called Dunmanisfestin. The various continents and cities of the Disc are always more than recognisable, despite some stunning rips in the space-time continuum: Ephebe and Tsort approximate to classical Greece and Rome. Genua is strongly reminiscent of New Orleans.

The small, rural kingdoms of Sto Helit, Lancre and Quirm insistently evoke the northern provinces of England. The desert kingdom of Djelibeybi is somehow overwhelmingly Egyptian, and the lost continent of Fourex brings immediately to mind Alan Coren's poignant operatic epic Oedipus Bruce. (‘Queen Glenda's me mum. I've only gone and married me flaming mummy!’).

The Disc is peopled by, well, people—and by witches, wizards, trolls, assassins, werewolves, elves, dwarves and every other stock character from fantasy, all of whom behave much like human beings, apart from certain species characteristics or an ability to practise magic.

Many of the books are set in the Disc's capital city, famously evoked in the quotation ‘A man who is tired of Ankh-Morpork is tired of ankle-deep slurry.’ Unseen University with its memorable faculty of huge and hugely eccentric wizards is located here. Several more Discnovels are based in the tiny agrarian community of Lancre, far away in the chilly Ramtopmountains. This is home to three of the strongest (in every sense) Discworld characters, the witches—kindly, salacious Nanny Ogg, stately Granny Weatherwax, and the droopy, New Age feminist Magrat Garlick. (‘‘When shall we three meet again?’ … ‘Well, I can do next Tuesday.’’).

The best-loved and most familiar characters do pop up all over the Disc in the other books. Death, in particular, appears everywhere and is a complete anthropomorphic personification, conforming exactly to expectations, apart from his horse, Binky. (He had tried fiery steeds but they tended ‘to set light to their own bedding and stand in the middle, looking embarrassed’.) Despite outward appearances these cannot really be called fantasy novels, partly because Pratchett is too intent on undermining all the conventions of the genre and partly because they mirror so effectively the current concerns of our own society. For example Men at Arms considers political correctness and equal opportunity employment, (for trolls, werewolves and so on) while Moving Pictures features the corrupt growth and widespread influence of Hollywood. Transposing such issues to another, wholly original, world is the creative equivalent of fuelling a huge blast-furnace single-handed.

Although accessible to any reader, the real delight of the Disc novels is the way in which Pratchett parodies and plays with all the tropes of literature and literary theory. Guards! Guards! satirises the noir-type private-eye novel, while Witches Abroad considers narrative causality in fairy-tales. Wyrd Sisters loosely utilises the plot of Macbeth, while Lords and Ladies is based, more substantially, on A Midsummer Night's Eve, detouring to attack the current tyranny of style in society by way of parallel—worlds theory. Although tightly plotted, each novel is classically baggy with content ranging through anything from myth, fable, particle physics, tourism, camel-driving and religious wars to the prevalence of shopping malls.

Literary parody is rampant—a famous scene from Tom Brown's Schooldays is re-enacted in Pyramids and wisps of Great Expectations drift through Mort.

Carpe Jugulum, which loosely translates as ‘Go for the Throat’, follows the now inimitable Discworld formula. Knowing that however stymied by CD-ROMs, modems or RAM, everyone knows exactly what to do when faced with a vampire, Pratchett proceeds to overturn our hoary certainties. Lancre is taken over by the vulgar, upwardly-mobile vampire family of the Count de Magpyre, attended by their unfaithful retainer Igor, a man of many parts—that is, he doubles as a Frankenstein's monster.

In aligning the witches to combat this new outrage, Pratchett finds Magrat, now married to King Verence, trying to combine her witching career with motherhood, having just produced Esmerelda Margaret of Lancre. Pratchett also manages to deal with the myth of the phoenix, the nature of sin, Scottish tribal wars, the dilemmas of the contemporary Christian Church, the cliches of monster films and the increasingly complex psychology of Granny Weatherwax.

Pratchett's position as a leading comic novelist now seems as permanently assured as that of P G Wodehouse. Naturally his extremely broad appeal and light contemporary touch ensure his readership but what exactly qualifies him for permanent print status? Successful serious literature deals primarily with character and personality. Changes in setting are affected by human nature and character development. (Consider, say E M Forster or Ibsen.) Comic literature, specifically modern comedy, reverses this process in that it is the setting that is of paramount importance. A situation-specific fictional world must be established, a closed system in which normal rules can be suspended and the wild rumpus begin.

For comic purposes this can occur in two ways. The setting can be fantastical and the humour arise through contrast with pragmatism, contemporary attitudes and down-to-earth detail. Such is the case with the Disc, with Cold Comfort Farm, Red Dwarf, Evelyn Waugh's California mortuary in The Loved One and the ludicrously exaggerated aristocratic world of Bertie Wooster.

Alternatively, the setting can be mundane—an hotel, a university, a river-trip—and the comedy ignite through the introduction of anarchic elements: thus Basil Fawlty, Kingsley Amis's Lucky Jim and Three Men in a Boat, not forgetting Montmorency.

So Pratchett's Discworld adheres closely to an established comic structure which allows him to comment on human society from a position of infinite flexibility. Unlike many humorists his fundamental attitude is kindly rather than misanthropic; he is quietly, unobtrusively ethical, and consistently promotes ordinary decency; he is highly amusing without resort to crude stereotyping. All this, aligned to his turbo-charged imagination and heightened awareness of literature and literacy, suggest that he will remain an enduring, endearing presence in comic literature. As Granny Weatherwax says ‘Words is important’.