In the book, it's easy. A flick of the witch's wand, and bingo - flesh becomes stone.
On stage, such magic needs a little more technical back-up. They've already dealt with the moment when the witch conjures a goblet of cordial and a box of Turkish Delight out of nowhere, using special trap doors and tiny gizmos that will release the goodies on cue. But turning an actress into a rock is more demanding.
It is not just the magic moments that make staging CS Lewis's children's classic a challenge, however. Far more daunting is the creation of the book's peculiar enchanted atmosphere - coupled with the tact that you are entering the perilous territory at the reader's imagination.
Lewis's story of the four evacuated children who stumble on Narnia at the back of a wardrobe is a memorable read. Anyone who encountered it as a child will remember that scalp-prickling moment when Lucy first pushes through the coats in the wardrobe and feels fur give way to fir.
Most will have a picture in their mind's eye of the bewitched forest where it is always winter. Ward's Narnia has to live up to that mental landscape.
"I tried to tune into how I felt about it as a child, rather than as a grown-up," he says. "I loved that almost eerie atmosphere that unsettles you and enchants you."
In a sense, Ward is accustomed to dealing with transformed worlds, having provided inspired sets for some of Shakespeare's most magical plays - the most recent being Adrian Noble's production of The Tempest Together, Noble and Ward have developed a distinct style: Ward designing a beautiful but very succinct set that supports Noble's uncluttered staging. Ward sees The Lion, The Witch and The Wardrobe, again directed by Noble, as fitting into the pattern, and again, his first instinct was that less would be more. But this time he had to suggest a surreal atmosphere, while also handling the fact that Lewis is very fulsome in his concrete descriptions at the Narnian forest. Too abstract a design could confuse the audience. To begin with, Ward was flummoxed.
"I thought, `Oh my God, how can I get all this world on stage?'" he admits. "I started off creating cone shapes made out of silk that would look like trees covered in snow. They were able to move, because you have a lot of journeys in the show. But the story moves so quickly that they became incredibly cumbersome. I started having to choreograph the set, which was really, really unhelpful.
"At the end of the day, the simpler you are, the more the characters and the story fill the space."
In the end, a chance discovery provided inspiration. "Knocking around in my studio I had some sea fern, which is very brittle. We were looking at photographs of winter landscapes where everything was covered in frost.
"We got the sea fern out and had a look at it in the model and it really seemed to deliver that story."
On the final design, the cold brittle fingers of the sea fern reach into the stage space from around a curved proscenium, giving the whole the beautiful, magical quality of a winter scene in a snow globe. It suggests a frozen landscape while leaving room for the audience's imagination. On the full-sized set, of course, the delicate fronds of sea fern will be metal, backed by a mesh that has been covered in a latex rubbery skin and malted with a heat gun.
For the technical departments, working on the design has provided a chance to let their hair down. This is the first Christmas show in Stratford for 30 years, and it makes a change from staging the Bard. A touch of Narnia has infected all the workshops. Parked in the props department is the witch's sledge, a fantastical winged chariot made of curled aluminium. In the wardrobe, eagles feathery legs and beavers' coats peep out from the rails of costumes. Sequestered in a fitting room lies the witch's white cloak, a vast, long-haired beast trussed up like a dead Yeti. It moults over everything, so has to be kept in solitary confinement. The shoe department, usually the repository for boots, buckles and armour, has had to come up with cloven hooves, centaurs' wings, and giants' legs.
But it is the hat department that has really come into its own. This small group of industrious women, usually responsible for bonnets and caps, has created a huge array of extravagant headgear. They have made ethereal tree spirits' headdresses, a unicorn's horn, modelled, rather poetically, on a melted advent candle; and the witch's headdress, a pointy, frosty tiara made from ostrich quills and optical fibres that shoot back from the actress's temples. "It makes a change from Tudor caps," says Elaine Moore, head of hats.
The most difficult task has been Aslan's mane. Aslan, the lion who breaks the witch's reign in Narnia, is not just a big cat, but also a regal and mysterious being; Lewis intended the story to be a Christian allegory in which Aslan is a representation of Christ.
The mane is not just a mane, but an aura - a halo even.
"We started off with lots of quills and feathers mixed with twine to get a light bulky appearance," says Moore. "But the yarns and twines made it too earthy and heavy. Now we're trying a mixture of feathers and fur."
Aslan has been a headache for Ward. He wanted to avoid the cuddly, fancy dress effect, yet to produce a recognisable lion. "One help was discovering that Patrice Naiambana was going to play that part," he says. He's got a very powerful presence, which made me realise that the costume doesn't have to be the powerful thing - you've got somebody strong playing the lion, now dress them as simply as you can.
No hairy breeches, then, but gold velvet trousers, and Naiambana won't have to mumble through a furry face. Solving Aslan determined Ward's approach to all the animals. The story calls for beavers, fauns, squirrels, and wolves, not to mention centaurs, dryads and a unicorn. Again,with the set, Ward realised that suggestion was the key: finding a way of giving the actor the same quality as the animal, without replicating it literally.
"We've hardly used any fur at all," he points out. "For the beavers, for example, we've used fringed trousers instead of furry ones."
One advantage of this non-literal representation is that it allows for the interpretation that Narnia arises from the children's imaginations - a possibility that comes into its own with the witch's army of baddies. Here the "Efreets, Sprites, Orknies, Wooses, Ettins" and their pals become sinister looking bogies in black gas masks, reminding us that the children have been evacuated from horrors more real than those in Narnia.
"Adrian was very keen that the war is ever present as a frightening thing going on in the real world," Ward explains, "so Maugram, the witch's chief of police, has a Gestapo feel to him, and when Mr Tumnus's house is destroyed it looks like an air raid. We came across a picture of a group of people all wearing gas masks and thought what a brilliant idea for the baddies."
Back in the workshops, there are more magic hitches to overcome. The revolving wardrobe, which is to spin the children in and out of Narnia, is in danger of doing too many revolutions and overwinding its mechanism, presumably stranding them in no-man's land.
Ward looks a little weary. When it comes to magic, it seems technical wizardry just can't keep up with spells.
`The Lion, the Witch and the Wardrobe previews from 24 Nov and opens on 1 Dec at the Royal Shakespeare Theatre, Stratford-upon-Avon (01789 295623).Reuse content