Terry's diner

The question becomes more understandable when you consider that, in what is supposed to be an interview about the Edinburgh premiere of the musical adaptation of his novel Only You Can Save Mankind, we have, so far, discussed the birth of ideas, the joy of the English language and the appalling state of literacy in society today. If conversation were edible, Pratchett would be its Valvona & Crolla. You might go in with a list that says "bread, bottle of Chianti, gorgonzola" but the place is just so full of tempting possibilities that you forget your list and instead revel in the sheer variety.

There is no character template for the creator of "fantasy" fiction. Lewis Carroll and Douglas Adams, JRR Tolkien and Terry Gilliam have little in common - apart from the ability to create worlds. Pratchett has, in his time, been compared to them all. For the record, he is a big fan of Terry Gilliam. And he has loved Tolkien’s The Lord of the Rings since he read it as a 13-year-old. "You just can’t really criticise The Lord of the Rings," he says. "Of course, you could list 12 things that are wrong with it. But you could list 12 things that are wrong with Mount Everest. What would be the point ?"

We canter down a tangent through children’s fiction. He was less thrilled by Narnia, hated Swallows and Amazons for being too posh - "prissy little voices and grey shorts" - but absolutely loved Just William, although the Browns’ cook and maid left them some way from the proletariat. He reckons William is timeless and would fit perfectly into contemporary storylines. "I could write six of them. William and the Hippies. William and the Illegal Immigrants..."

Pratchett is a bit timeless himself. This is the man who wrote that "Age and wisdom don’t necessarily go together. Some people just become stupid with more authority." Not Pratchett. Age suits him. He is 56, with pockets of 26 and just a hint of 76. He has that directness that comes with extreme youth or post-middle age. We are sitting where he writes, all high vaulted ceiling, vast wooden beams and seasoned stone. Despite its ancient look, he is having this work in progress built by local craftsmen. It is masterly work by tradesmen using skills that are fading away. "We need more joiners like these," he says, pausing to admire his curving staircase. "Fewer journalists and more joiners!" He sits in front of an antique, leather-bound edition of the Encyclopaedia Britannica and behind a triptych of flat, eye-level computer screens. The position suits him. Pratchett is a disciplined writer, once he starts, although he does require what he calls "bubblegum for the mind … something to do while I’m thinking." The Pratchett mind chews computer on games and long walks.

He moves to a high-backed leather chair opposite me and starts the hand-rubbing thing. I ask if he needs a quiet, almost inspirational place like this to write. "Ah, you’re on the wrong tack there," he pounces. "That’s not how ideas come. Ideas come from a thought, a phrase … from something small happening. Not from being in a place. If I visit an ancient castle, that’s not going to give me ideas. That’s just stuff."

Pratchett’s "stuff" has, of course, sold more than 30 million copies in 27 languages worldwide, making him the UK’s top-selling author of fiction and winning him the ultimate accolade - on the BBC’s The Big Read, only two authors had five of their books nominated in the top 100 novels. The other was Charles Dickens.

It is striking how pitch perfect is Pratchett’s use of language. But the sheer inventiveness of Discworld and its characters, plus the whitewater irresistibility of the storylines, tends somewhat to mask that. Pratchett has a genuine love and respect for the English language. "French is the language for making love. But then you’d only want to do that for …" and those hands open in a gesture of positively Gallic expressionism, " … three or so hours a day." A knowing pause. "But as a sort of Swiss army knife of communication, you can’t beat English."

He thinks for a moment. "Glint … gleam … glisten … glimmer … In most languages there would only be one word," he observes. Impudent is another one he likes. "You can tell a lot about a character by having them use the word ‘impudent’."

He is a fan of Lynne Truss’s hit book Eats, Shoots and Leaves. Many years before her paean to punctuation topped the bestsellers list, Pratchett had noticed how haphazard was the application of the apostrophe on the average greengrocer’s price tickets, leading him to create a fictional family of greengrocers whose speech was carefully, atrociously punctuated.

"You know there are young people getting by on a vocabulary of 500 or 600 words," he says. "There are thoughts you simply can’t formulate properly on a vocabulary like that. Feelings you can’t express. So they bottle it up … they get frustrated." He despairs of a society that obsesses with the details of what young people are eating, but not "about what goes in through their eyes. Their brains are being fried by television."

Earl Grey tea and his wife’s delicious honey cake have been brought. I nearly choke on them as Pratchett describes getting a Media Studies degree as almost "like going to the toilet. They may as well have a roll of paper on the wall and you can just tear off a square that says ‘Media Studies Degree, please help yourself’."

We go to a local pub for lunch. Pratchett is well known and well liked in the area around his country manor home. He and his wife live the full Aga-fired, vegetable-gardening, preserve-making life. His preserves are almost as renowned as his wife’s baking. He has a bit of a thing about condiments, regarding a decent salad dressing as "why God made lettuce".

There is a wonderful moment at lunch where life echoes art. Terry’s Thai green curry arrives, and our friendly landlady warns firmly of the danger of our extremely hot plates. As his fingers shoot forward instinctively to touch china, I think of something from The Thief of Time: "Some humans would do almost anything to see if it was possible to do it. If you put a large switch in some cave somewhere with a sign on it saying ‘End of the World Switch, Please Do Not Touch’ the paint wouldn’t have time to dry."

Pratchett is watching carefully as I wrap myself around a pint of local cider. He lived for a while in the Mendips, he says, where one local workman used to drink 25 gallons of the stuff a day. He drinks brandy.

He hopes to visit Edinburgh to see Only You Can Save Mankind. At any given time there are, he says, around 20 stage adaptations of his books. He tries to see as many of them as possible. There are regular enquiries about film rights to his books, "but very few who really want to make a film," he says. He doesn’t approve of the movie world’s penchant for buying up rights purely to stop someone else getting them.

Pratchett is, of course, writing another book, and tours pretty regularly - especially in Australia, where he seems to have a particularly huge base of readers and fans. "Fans are the ones who buy the T-shirts," he explains. He thinks about stopping but "I wouldn’t know how to define myself". What he would like to have less of is "the business of being a writer" which, he says, at times takes up more hours in the day than the writing itself. Nine-tenths of the universe is in fact the paperwork, someone once observed. Oh yes, it was Terry Pratchett.

Terry Pratchett’s Only You Can Save Mankind is at the Pleasance, Edinburgh, 4-30 August.