Interview: John Stevenson, director, Kung Fu Panda

He describes it as a "flea pit", but it was in the darkness of Hayward Heath's former Perrymount cinema that John Stevenson saw his future flash before his eyes.

The film was The 7th Voyage Of Sinbad, Nathan Juran's wondrous 1958 tale of roaring cyclops, four-armed snake women and sword-wielding skeletons. He came in, as always, part-way through (his mother having a "whimsical" sense of timekeeping), just as Ray Harryhausen's stop-motion animated cyclops was roasting a man on a spit. For a child obsessed by drawing and film, the experience was an epiphany in Glorious Technicolor.

"Everything that was in my imagination was up there on the screen," he recalls, "and I didn't really understand how it worked, but I was like, that's what I see in my head. I want to do that."

As he recalls the episode, John is sipping coffee in a palatial suite at Knightsbridge's Mandarin Oriental hotel, where he is promoting Kung Fu Panda, his directorial debut for American animation giant DreamWorks. One of its stars, Hollywood actor Jack Black, is being interviewed by a stream of chattering journalists in a nearby room. Posters advertising the film whiz past the window on the sides of double-decker buses. This, one realises, was a childhood ambition more potent than most.

Now a married father-of-two, John, 50, grew up in the sleepy Mid-Sussex market town of Cuckfield, where his mother still lives. He was TV-fixated - even teaching himself to draw by copying characters from cartoons - and hell-bent on realising his early dream. "I was just stuck on the idea that this was what I was going to do," he says, "though it seemed a somewhat unlikely career in 1960's Cuckfield. I'd say I was going to draw moving monsters and people would say, That's nice dear... I hear Woolworths are looking for staff.'"

After schooling at Great Walstead in Lindfield (he remembers an inspirational art teacher known as Miss Mackintosh), he transferred to Warden Park comprehensive, the memory of which darkens his face even now. He left at 16 - "I was a bit of a thicko - the only thing I could do was draw" - to join a London film studio as a runner. Then, three years later, he got the fabled "big break". Flicking through a trade mag one day he noticed the London office of Jim Henson Productions - which made the hugely popular Muppet Show - was advertising for staff. "I loved The Muppets," says John.

"I'd encountered Kermit before in the Muppets' Cinderella and fallen in love with him. I would go through TV Times and Radio Times every week to see if there was anything with him in it."

He managed to land himself the job and spent more than ten years there as a storyboard artist and character designer.

Working first on the Muppet Show TV series (the character of Dr Bunsen Honeydew's hapless assistant Beaker was supposedly based on John), he went on to do films including Dark Crystal, Labyrinth and Little Shop Of Horrors. The late Henson would come up with ideas for characters and John was one of the people responsible for realising them. "Jim would say he wanted a tapdancing walrus, I'd design it and if he liked it, we'd build it," he says. "It was amazing - that magical thing of seeing what you'd drawn brought to life."

Henson, with his brilliant imagination and famously egalitarian, hands-on approach, was, and continues to be, a huge inspiration to John. "Everything of any value I've learned professionally or personally I learned from him,"

he says, "I was very lucky at 19 to see a man working at the height of his powers in the most successful show in the history of TV at that time.

"It's an overused word these days but Jim was a genius, in the same way that Walt Disney was - someone who was able to change culture by the power of their imagination.

"He was also the world's nicest guy and led by collaboration and appreciation. The huge lesson I learnt from him was you can have it all and still be a decent human being."

John eventually left Jim Henson Productions and moved to the US where, in 1999, he was taken on by DreamWorks as head of story, working on the studio's first wave of animated blockbusters such as Shrek and Madagascar.

Several years later, he asked DreamWorks's animation chief Jeffrey Katzenberg for his chance to direct and paired up with colleague Mark Osborne (best known for stop-motion short film More) to direct Kung Fu Panda.

Four years in the making, it is a classic triumph-over-adversity story of Po (Jack Black), a chunky, clumsy panda who works in his family's noodle shop but dreams of being a kung fu hero. When he is mysteriously chosen to fulfil the ancient role of Dragon Warrior, his dreams become reality. Under the tutelage of kung fu guru Master Shifu (Dustin Hoffman), he begins to study alongside his idols, the legendary Furious Five - Tigress (Angelina Jolie), Crane (David Cross), Mantis (Seth Rogan), Viper (Lucy Liu) and Monkey (Jackie Chan). His new-found skills are soon put to the test when evil snow leopard Tai Lung (Ian McShane) appears, intent on vengeance, and it falls on Po to defend everyone.

The idea had been knocking around the studios for some time, but hadn't quite found its way out. Initially pegged as a parody, John and Mark didn't feel that would do it justice and decided to play it as simple comedy. Both huge fans of martial arts films, they wanted to make something that was - as much as possible where animated animals are involved - a homage to the genre. "I wasn't interested in making fun of them, because I really think martial arts movies can be great films," John says, "So we said, let's take Kung Fu Panda, which is an idea everyone gets comedically, but then let's try and surprise everybody by giving them more movie than they might expect from the title. Let's try to make it a real martial arts movie, albeit one with a comic character."

Fight choreographer Rodolphe Guenoden supervised the animators and story artists, at times modelling poses to illustrate how a move should look. He also came up with one of the film's main conceits, that the animals in the Furious Five should perform the martial arts styles named after them. So one sees, for example, a snake fighting in the style of a (human) kung fu interpretation of a snake.

"One of the big concepts of the film was to use the five original animal fighting styles," John says, "The Furious Five in the film actually personify them. It was kung fu in such a way that honoured its source, but it also did it in a way you've never seen before because it was animals doing it instead of human beings." Getting Jack Black to voice Po was key to the film. The rotund, wild-eyed comic actor known for playing lovable eccentrics in films including School Of Rock, Be Kind Rewind and The Holiday, John and Mark felt he was ideal to bring their lead to life. He did, however, tone down the full "Jack Black" experience for the role, choosing to take a more vulnerable, humble tack. John says: "I think there's always this glimpse of that kind of character inside Jack, but most of his characters like being abrasive. He ended up being this very lovable and easy to relate to character, heavily laden with insecurities."

Kung Fu Panda opened in America last month and is set for UK release today. After four years - not to mention decades in the build-up - it must, I suggest, feel a momentous achievement.

"It seemed a far-fetched dream growing up in Cuckfield, where you'd look out of the window and all you'd see was a cow steaming gently in the afternoon rain, and I was there thinking about making movies in Hollywood," John muses.

But he says, steering the conversation rather neatly back to Kung Fu Panda, "That's kind of the movie really - it doesn't matter how crazy your dream is, don't let anyone talk you out of it."