James and the Giant Peach: Just how do you make Roald Dahl's giant peach?

A fuzzy 8ft peach takes centre stage at the Royal Festival Hall in an event to mark the centenary of Roald Dahl's birth. Adam Lusher discovers the secrets of how it was made

The peach in pieces

James Henry Trotter had it easy – even if his parents were eaten up (on a crowded street, mind you) by an enormous angry rhinoceros which had escaped from London Zoo; and even if he had to live with Aunts Sponge and Spiker, who were both really horrible people.

To make his giant peach he just needed a bag full of “one thousand long slimy crocodile tongues boiled up in the skull of a dead witch with the eyeballs of a lizard”, to which were added “the fingers of a young monkey, the gizzard of a pig, the beak of a green parrot, the juice of a porcupine, and three spoonfuls of sugar”. Then (accidentally) drop your tongues near an ancient peach tree and, hey presto, one giant peach almost as a big as a house.

Outside the pages of James and the Giant Peach, however, it ain't that simple – even if you are creating the star exhibit of The Wondercrump World of Roald Dahl, which opens today at the Royal Festival Hall, the curtain-raiser for a nationwide “Roald Dahl 100” celebrating the centenary of the author's birth.

With the above ingredients in short supply on London's Southbank – porcupine juice being more of a Hoxton thing – you have to go to a props studio in an industrial park in Streatham Vale, south London. And, says Russell Beck, 59, head of the Russell Beck Studio, you start, not with crocodile tongues, but with an 8ft by 8ft by 8ft cube of polystyrene. You cut that into a ball, carve out the fine detail using the studio's specially created brushes – “They look like paddles with nails on” – and then you create what Paul Denton, the Wondercrump producer, had ordered: The Squirm.


 The peach being made

Denton was very particular about his Squirm. He'd decreed that everything in this immersive show for seven- to 12-year-olds should have at least one of the effects Dahl sought in his own writing, to make you tense, enthralled, laugh or squirm. And the peach was to supply The Squirm, experienced by putting your hand into a grub hole in the peach. I am sworn to secrecy about its precise nature. Suffice to say it would appeal to non-scaredycats who like surprises of the gooey, multi-legged kind.


 Tales of the unexpected: children try out the peach (Rex)

In the book, James got his grub hole ready-bored by a collection of giant creepy crawlies.Beck had to get more Heath Robinson. “We took a bit of drainpipe,” he says, “and shaped its edge so it was serrated. Then we connected the other end to a power drill and used the sharpened pipe as an enormous drill bit.” Next came the top secret part – not the painting, but the application of a marvellous “texturing mixture” to give the polystyrene a proper fuzzy, furry peachy look.

Construction took two weeks. Then they had to get their peach to the site – not hoisted in the air by 502 seagulls, as in the book, but driven in a Luton van, by a bloke called Charles. “He's the best,” says Beck, “if you want your prop to arrive undamaged and in one piece.” Except it didn't arrive in one piece. It arrived in three peach segments, because the venue doesn't have 8ft wide doors, and Denton was very particular about its structural integrity.

Now glued back together, the giant peach awaits its visitors. The exhibition will run until the summer. The giant peach is in the forest. Watch out for The Squirm.

'The Wondercrump World of Roald Dahl' is at the Royal Festival Hall until 3 July