Roald and the story factory

Characters that disappear, plots that change and doors that look like chocolate. It sounds a bit like a tale from a master story-teller

"What you want to do is write a children's book. That's where the money is today." Thus Roald Dahl, balefully recorded by Kingsley Amis with lip-smacking relish along with other breezy advice about how easily "the little bastards will swallow it". For Amis, this was welcome proof of Dahl's pervasive cynicism, although he does grudgingly add his next comment: "Unless you put everything you've got into it, unless you write from the heart, the kids'll have no use for it. They'll see you're having them on, and just let me tell you from experience that there's nothing kids hate more than that."

Amis remained unconvinced, but might just have changed his mind had he lived to visit - admittedly, a very unlikely event - the new Roald Dahl Museum and Story Centre opening this weekend in Great Missenden, Buckinghamshire. Set in an old coaching inn near Gipsy House, Dahl's home from 1954 until his death in 1990, it is a monument to hard professional work, leavened by the wild and often unpredictable sense of humour of an essentially restless spirit. Although Dahl made a bonfire every month of the various first drafts with which he had wrestled, enough paperwork remains to stock a huge archive, now housed in a special Story Centre within the museum. Here visitors can see for themselves how over the course of a year - the average time Dahl took to write a children's novel - ideas change, characters transmute and original plots sometimes end up standing on their heads.

This is particularly true of Dahl's most famous children's book, Charlie and the Chocolate Factory. After finishing a first version, he lent it to his young nephew who duly reported it "rotten and boring". Undiscouraged by a verdict which sounded very like his own opinions about some of his fellow authors, Dahl got on with the rewriting, during which time 15 unpleasant child characters, including the future hero Charlie Bucket, were reduced to five. Lost along the way were Wilbur Rice and Tommy Troutbeck, both ending up on the wrong side of the "Pounding and Cutting Room", Clarence Crump, Bertie Upside and Terence Roper, who fatally overheat after cramming in mouthfuls of "warming candies" and Marvin Prune, a conceited boy discarded before a suitably horrible death could be devised for him too.

This story, like all the others, was written in a brick hut built for Dahl on the edge of the orchard at the bottom of his garden. An exact copy of Dylan Thomas's writing hut in Laugharne, once visited by Dahl, a cross-section of it is now reproduced in the museum, surrounded by paper trees created by Quentin Blake, Dahl's regular illustrator. With its yellow front door and sheets of polystyrene lining the walls, it is a mixture of the barely tolerable and the thoroughly uninviting. Its single seat has a hole in it, to prevent pressure on an abscess that had formed on the base of Dahl's spine. A green baize writing board, designed by Dahl, was the only object that was ever cleaned - Dahl used an old clothes brush to sweep off the scraps of rubber accumulated from rubbing out his writing. Otherwise the hut was never dusted and remained, with curtains drawn, strictly out of bounds to everyone else. Within it, Dahl worked from 10.30am to midday and then from 4 to 6 pm. An electric fire on the ceiling, which he could pull towards him on wires - another invention - provided the only heat. The footrest, made from an old suitcase filled with logs, and the green sleeping bag into which he often tucked his legs are not on display.

This replica hut also contains an exact copy of Dahl's "Treasure Table", on which he kept a collection of objects ranging from part of his own hip joint - said to be the biggest the surgeon performing his replacement operation had ever seen - to a giant ceramic aspirin. All are now carefully reproduced and annotated, to be picked up by the curious and then replaced like pieces in a large jigsaw. Elsewhere in the museum there are reminders that Dahl could never spell ("arithmatic", "your's") plus a collection of his favourite "knock knock" jokes and bawdy limericks.

Dahl was always on the edge of bad taste or sometimes well beyond, once describing Iris Murdoch as "a silly old hag" for her low opinion of the value of children's books and opining that where the Jews were concerned, "even a stinker like Hitler didn't just pick on them for no reason". The first popular author since Chaucer to describe farting with uninhibited good humour, his popularity with child readers has always exceeded his reputation among his various adult critics.

But however occasionally outrageous in and out of print, all the evidence on display in the museum clearly shows that Dahl only got where he did - 90 million sales worldwide plus a further million a year since his death - through the solid grind of endlessly polishing and then repolishing his written texts. First trying out his stories on his own children at bedtime, he liked to start each novel with a truly attention-grabbing sentence, such as: "What a lot of hairy-faced men there are around these days" (The Twits), or: "Until he was four, James Henry Trotter had a happy life" (James and the Giant Peach).

Also skilled at writing verse, Dahl finally perfected, after much trial and error, a type of easy prose rhythm largely absent from the pages of his best-selling modern successor J K Rowling. But both authors write well about food, that standard substitute for sex in novels addressed to pre-adolescent readers. A chocolate-taster for Cadbury while he was still at school, Dahl's lifelong passion for this emperor of all the sweets is reflected in what look like chocolate- covered doors leading to the main room in the museum. An atomiser above wafts out discreet chocolate smells, just to make sure the point is not lost.

There are many other surprises, such as the painted shadow of the BFG (Big Friendly Giant) that looms over the museum entrance, a crocodile disguised as a bench and a carpet modelled on the American yellow legal pads Dahl always used for his writing. But what would also have pleased him are the many opportunities for the young to create something themselves. A shadow puppet theatre is available for made-up plays, and an Ideas Table is there for writing stories. Animation technology is also at hand, and there are ingenious bottles for recording those extra special dreams. With writer-in-residence Val Rutt there to give advice to visiting groups, it seems certain that this brilliantly interactive museum will be well patronised by children as well as by scholars attracted to what is already one of the largest literary archives in the world. And with the new film version of Charlie and the Chocolate Factory, directed by Tim Burton and starring Johnny Depp, due to be released this summer, life in Great Missenden High Street seems set to become even busier in the months to come.

Nicholas Tucker is the author of 'The Rough Guide to Children's Books', 0-5 years and 5-11 years.