ABOVE Jasper Fforde's farmhouse in the Welsh hills, the sky is leaden grey. "Like living inside Tupperware," he says. "There are no shadows. We won't see shadows until May. And then, because Fforde is a chirpy sort, he adds: "Still pleasant, though."
I might go as far as to suggest that if any writer had to be sentenced to life in a Tupperware box, Fforde would cope better than most, so colourful are the worlds of his imagination. This is the man who found the potential for a whodunnit in a nursery rhyme (Did Humpty Dumpty fall, or was he pushed?) and reinvented Swindon as the glamorous, high-powered "jewel of the M4". His quaint, endlessly inventive humour has earned him comparisons to Douglas Adams.
Fforde writes what might be described as comedy-fantasy-crime books (though he says he hates genres – "the measles of the book world"). Reading a Fforde novel feels like taking off on a magic carpet, only to be picked up by another and another and taken on new flights of fantasy. If you think too hard about it, it can feel like someone is trying to pull your brain out through your ears with a crochet hook: you might experience this when I try to explain his latest plot.
First, some background. In Fforde's first novel, The Eyre Affair, he invents a literary detective called Thursday Next (he keeps "a notebook of silly names") who finds out that the characters in Jane Eyre are going missing, and must enter the world of books in order to recover them. She is based in Swindon (where else?) in a Britain of the 1980s where the Crimean War has been going on for 131 years and people clone dodos as pets. So far so good.
His new book, the sixth Thursday Next novel, One of Our Thursdays is Missing, takes the whole idea a step further. Thursday Next is herself the subject of a series of true-crime books which, like all books, exist in the parallel universe of BookWorld. When the detective herself goes missing, her BookWorld doppelganger, the "written Thursday", must journey to the RealWorld to find her.
The odd thing is, when you're reading, none of this is an issue. When the plot is thundering along, peppered with jokes, lively dialogue and more silly names (the series includes a love-interest called Landen-Park Laine and a supercilious corporate henchman called Jack Schitt) you just sit back and enjoy the ride.
"It's very strange," says Fforde. "I thought at first this book was going to be overly complex. But no matter how complicated I make the books, as long as the internal logic holds together, readers are OK by it. People who read my books have an open mind when it comes to new, bizarre, interesting and exciting ideas."
Fforde, 50, spent 19 years working as a cameraman on big-budget blockbusters like The Mask of Zorro, Goldeneye and Entrapment before The Eyre Affair was published. He has clocked up ten novels in as many years, with sales in excess of two million, and is translated into many languages including Chinese and Hebrew. In addition to six Thursday Next books, there are two Nursery Crime novels (featuring detective Jack Spratt and his sidekick Mary Mary), Shades of Grey, a Brave-New-World-style novel about a society in which everyone is colour blind, and The Last Dragon Slayer, a fantasy book for young adults.
Ideas are not something he's short of, and the "Fforde fiction factory" in the hills above Hay-on-Wye is extraordinarily productive. Both Shades of Grey and The Last Dragon Slayer are the first of a trilogy, and he is commited to turning out two books per year, with titles planned until 2014. He and his wife Mari run the comprehensive website (jasperfforde.com) and produce a range of Thursday Next merchandise.
He says people keep telling him that his books are postmodern, tossing out words like "intertextuality". "And I have no idea what they're talking about. I just write books and I do it without any notion of what I should do or shouldn't do. I left school at 18, I don't have the benefits or drawbacks of a university education. I just write what I hope amuses me, and I hope will amuse others." He is an entertainer, he says. The word which keeps reccurring in our conversation is "fun".
One of Our Thursdays is Missing started because he thought up the title, and thought it "sounded fun". From that developed the idea of Written Thursday, a nice, cardigan-wearing girl who is struggling to keep her series off the remainder shelves. She must discover whether she has the strength to be a hero like the Real Thursday, whom she idolises. "It's like having an elder sister who's better than you and you're trying hard to live up to that. It's an odd way of playing with that whole sibling dynamic."
He also has a great deal of fun with BookWorld itself, where the genres all have geographical territories, administered by the shadowy Council of Genres. Comedy is depleted of laughs, due to an upsurge of stand-up comedians in RealWorld, Horror has had a boost due to the burgeoning Urban Vampire sector, and there is a dangerous political situation developing over in Racy Novel.
"I work very much on the principle that anything created by mankind has mischief and error hardwired into its inception. The characters in the books that we've written are very much like ourselves. Smaller characters want bigger parts, and if your genre is shrinking you start blaming other people for the reason you're not popular. You can have a geo-political jab at this notion of all the nations of the earth fighting amongst themselves over rather pointless ideas. I think I reflect that in BookWorld."
Fforde wrote for ten years before The Eyre Affair was published, completing seven books and garnering 76 rejection letters. "A lot of people say, 'Why didn't you give up?' My answer is that I never once thought of giving up. I wasn't writing to be published, I was doing it because I love writing. I look back on those times not as me not being published, but as Jasper learning his craft.
"When I look back at what I wrote in the early part of these years, it was very dodgy, but you can see that there is a spark there. It wasn't so much the publisher suddenly discovering me as me suddenly presenting a book that they could say: 'We can make this work.'"
Is it really as much fun as you say? "It's fun and it's work as well. It's very intensive hard work. But the other side of it is that, especially for me writing fantasy, you can let the seven-year-old in you run wild. The wonderful thing about writing the Thursday books is that it's a very broad canvas – no matter what I dream up I can somehow sniggle it in."
Take robots, for instance. Or psychotic mime artists. Or talking dodos. But let's stick with robots for the moment. "I always wanted to have a robot somewhere. So I like the idea of Sprockett the clockwork butler, who doesn't really understand about compassion and sentiment, but makes a very good cocktail."
And then, because this is Jasper Fforde we're talking about, he takes it a little bit further. "What would you worry about if you were made of clockwork? Honey would be highly dangerous to your insides. So there are jokes there.
"People say, 'What is your chief source material?', I'd have to say it's everything. Any author is a product of their life until that time. I hugely enjoyed Douglas Adams and Monty Python growning up, but also hugely enjoyed a lot of the sitcoms in the Seventies, literary classics, Tintin, aviation, popular culture. All that is part of the spectrum of experience that makes up me and the books I write."
The intriguing thing about Fforde's books is that they are both silly and highly erudite. He knows his classics, and respects them as well as lampoons them (he calls it being "reverentially irreverent"). He's not interested in literary recognition ("Fantasy writers don't really get much, so I'm not really troubled by it") and full as his books are of postmodern twists and turns, no-one regards them as offputingly highbrow.
He is extremely attentive towards his fans, who are loyal and very communicative. There have been several weddings of Fforde fans, he says, and there is at least one baby Thursday. There is an annual convention, the Fforde Fiesta, in Swindon (where else?), where people dress up as characters.
"Last week I got a letter from someone in the United States, talking about her parents, who have been married for 55 years. Her father reads to his wife every night, and they've been working their way through my books. Every year, on their anniversary, he writes a poem for his wife, and this year the Thursday books were featured in the poem – so they sent me a copy. It's hugely gratifying that the books can touch someone in that way. An email like that is worth 12 awards."
That's my one quibble with his fictional BookWorld: the Thursday Next series is so unpopular it is in danger of being remaindered. Flights of fantasy I can cope with, but Jasper Fforde not being read? Now, that really would be hard to believe.
• One of Our Thursdays is Missing, by Jasper Fforde, is published by Hodder, priced 16.99. Jasper Fforde is appearing at The Main Street Trading Company, St Boswells, on 3 March at 7:30pm; Waterstones West End, Edinburgh, at 12.30pm; and Aye Write! Book Festival, Mitchell Library, Glasgow at 6pm, both on 4 March.