When Tim Burton completed the filming of Charlie and the Chocolate Factory he wasn't so worried about getting the critical approval of the producer and Warner Bros Pictures but from the Dahl family.

Burton says: "I was more nervous showing them the movie than the studio just because it's their baby, so to speak. I was really nervous, but they were great all the way through. Felicity is a really great person."

Felicity Dahl, the late Roald's wife, had a huge input into the film and she took on the role of executive producer.

She says: "An adaptation like this is daunting because I don't think there's a child in this world who hasn't read the story or knows about it. Every child wants to be Charlie."

Felicity and the Dahl estate were involved in the whole process of the filming.

A spokesperson from the Roald Dahl Museum says: "The film company can't make the film without their approval. Felicity had a very good working relationship with Tim Burton and Warner Bros. Once she was happy with the screen play and happy with Tim Burton and happy with Johnny Depp playing Willy Wonka, then Tim was given artistic licence to make the film."

Felicity is very pleased with the way Burton has adapted her late husband's work, which Roald Dahl wrote in his writing hut in Gypsy Cottage in Great Missenden in 1964.

Felicity says: "All books have to be changed a bit in making a film. The important thing is that the alterations enhance the story rather than detract from it, and I believe that's what Tim has done here. When you choose someone like Tim to make a film, you choose him for his creative ability so you have to give him your trust."

The filming took place at Pinewood Studios where Burton and his crew took over seven stages and much of the back lot at the studios in Iver Heath including the James Bond stage, which houses one of the largest soundstage pools in the world.

For the exterior of the factory the film unit used a disused Nestle factory in the north of England.

ABOUT THE AUTHOR

Roald Dahl was born in Wales of Norwegian parents.

He spent his childhood in England and, at the age of 18 went to work for the Shell Oil Company in Africa.

When World War Two broke out he joined the Royal Air Force and became a fighter pilot. At the age of 26 he moved to Washington DC where he began to write.

His first short story which was about his adventures during the war was bought by The Saturday Evening Post.

At first he wrote stories for adults and then he turned his hand to writing children's books in the 1960s.

He wrote his books in his writing hut at his home in Gypsy Cottage, Great Missenden. The most famous are James and the Giant Peach, Matilda and The BFG.

INCREDIBLE FACTS ABOUT THE FILMING

Depp wore violet-tinted contact lenses

The chocolate river was made to a secret recipe of water, dietary cellulose and food dyes which smelt very bad

They used 200,000 gallons of flowing chocolate; approximately 32,000 for the waterfall and170,000 for the river, which measured 180ft long.

One actor, Deep Roy, played all the Oompa-Loompas in separate takes.

The Oompa-Loompa are to a scale of 30 inches high.

Forty real squirrels were trained to take part in one scene where they cracked open nuts.