Andrew Adamson: The man bringing Narnia to the big screen

It is 9.45am on a crisp November morning in Buckinghamshire, but for Andrew Adamson, who has recently arrived from LA, it feels hours earlier. The amiable New Zealander is nonetheless in chipper form. In fact, were we not here to talk about The Chronicles of Narnia: The Lion, the Witch and the Wardrobe, there would be little to indicate that it is less than a week since Adamson delivered his finished cut of one of the year's most eagerly awaited blockbusters.

The huge weight of expectation, from studio executives and fans of the CS Lewis book to the author's estate itself, would surely be enough to crush most people. However, the likeably laid-back Adamson is taking things pretty much in his stride. "I felt pressure making the film but now there's nothing I can do. So there's no point worrying," he says, shrugging. "Definitely as we get close to release I will get nervous about how it's accepted. But I feel like I've made a film that is truthful and faithful to the book, and that I like. Now it's up to the world to decide if they like it or not."

There is a lot riding on the $150m movie. Adapted from the second of the seven books in Lewis's beloved Chronicles of Narnia, it represents the first step in Disney's bid to build a franchise in the mould of Harry Potter, or the multi-Oscar-winning The Lord of the Rings, which the studio must still be kicking itself for turning down. The film is also a first for Adamson, as it marks his live-action feature-directing debut, following his success with the computer-animated Shrek movies. When I suggest that Walden Media, the film's co-producers, took a risk hiring him, he does not entirely disagree.

"I think it was somewhat of a leap of faith," Adamson concedes, "but I think they basically saw that storytelling is storytelling, and you use whatever tools are available to you to tell the story well. Basically, I got this because of Shrek and, I think, Doug Gresham [CS Lewis's stepson], from the estate, liked Shrek. I think they saw in that a fantasy story that had a lot of heart."

Adamson also just happened to be an ardent fan of the Narnia books. He first encountered them when he was eight, and fell in love with them immediately. He remembers his reluctance to finish the final book, The Last Battle, and having to decide whether "I was going to put it down and start all over again, or just kind of leave the world." Returning to The Lion, the Witch and the Wardrobe as an adult, Adamson was shocked by how much smaller the book now seemed. "It's like visiting a house that you lived in as a child."

What appealed to him most, reading the book as a boy, he says, was the feeling of empowerment that he drew from the adventures of the Pevensie siblings: Peter, Susan, Edmund and Lucy. After being shunted helplessly around during the Blitz, the evacuated Londoners enter Narnia, where they are greeted as kings and queens. Suddenly, the fate of the world is in their hands.

"Everyone is in awe of them. Everyone's waiting for them to solve all of their problems. While it's a big shift in responsibility, I think responsibility is empowering for kids," says Adamson. "It's basically saying: 'We trust you to make the right decisions.' I think that, as a kid, is pretty cool. Plus you get swords."

Adamson, 39, has become a father of two since starting the project, and he thinks that the Lewis books have a lesson for today's parents. "We're somewhat patronising to children. While you never want harm to come to your kids, if you over-protect them, they're never going to learn to look after themselves."

It surely took a lot of confidence to take on a gold-plated classic like The Lion, the Witch and the Wardrobe. But how does one put one's own imprint on something so beloved while still remaining faithful to it? Adamson admits that he was daunted by the prospect of finding a solution to this problem. But, importantly, Lewis stops short of describing certain pivotal events in full and chooses instead to "plant a seed and allow it to grow" in the reader's imagination. This meant that Adamson could exercise his own creativity in filling in the gaps, but he still had to be careful.

"The difficulty is there's a hundred million people or so that have read this book," he says, "all of them with their own interpretation, all of them with their own impressions, their own imaginations, and it was very challenging knowing how to do it in a way that wasn't alienating to some people."

To Adamson's shock, one of Lewis's biggest omissions was a description of the battle between the forces of good, led by the messianic lion Aslan, and the White Witch's evil hordes. In the director's mind, the battle had achieved epic proportions, something he now attributes to seeing Star Wars not many years after reading the book. "But when I came back and read the battle in particular, it was like there's a page-and-a-half of Peter telling Aslan what happened while he was away, and that's it. I was flicking backwards and forwards through the book, going: 'Wait a minute, where's the bit where all the mythological creatures fight? Where's the description?' Strangely enough, there's a lot of description about breakfast," he laughs, "but not a lot about the battle."

According to reports, the Lewis estate had for some time been leery of Hollywood's desire to make a live-action version of The Lion, the Witch and the Wardrobe. And no wonder, when an early screenplay had the children escaping from an earthquake in LA rather than the Blitz. There were even rumours of plans to cast Janet Jackson as the White Witch. "I was very unhappy, because I read some of those earlier versions, while doing visual effects, and it was very distressing," recalls Adamson. When Harry Potter and The Lord of the Rings hit the jackpot, studios in America began to accept that it was possible to take English literature, adapt it faithfully, and still have it be commercially viable. "The success of those films has somewhat given me licence to do that in this case," says the director, "whereas other people were trying to find ways to fit a square peg into a round hole. That's what the estate objected to. They didn't want Edmund asking for hamburgers is what it really comes down to."

Perhaps there was also concern that Hollywood would neglect or somehow distort the book's religious framework. Lewis was a devout Christian and the Chronicles can be viewed as a version of the biblical story. The film, though, though, needs to appeal to a broader audience than just the faithful. This may explain why Adamson becomes defensive when I bring up the subject of the story's Christian underpinnings. "What people are calling allegory is less present in this book than it was in The Matrix," he argues. "There you had this character Neo, he was chosen, he died, he came back, he saved the world: that's the Resurrection story. In The Lord of the Rings there's a resurrection story. In Star Wars there's a resurrection story. It's only because of who Lewis is that this is considered any more allegorical than any of those stories. I just think it's the climate right now that has brought attention to that."

But didn't they hold special presentations, I ask Adamson, at least one of which he took part in, to assure Christians that Lewis's vision would reach the screen intact? (Interestingly, as well as the soundtrack, a separate CD of music performed entirely by Christian acts inspired by the Narnia stories has been released.) "We assured a lot of fans of the book, both faith-based and not," says Adamson, clearly becoming irritated by the subject. Whatever the truth, Adamson's film is a triumphant piece of fantasy film-making that even Lewis, who once wrote, "there is death in the camera", might have enjoyed.

'The Chronicles of Narnia: The Lion, the Witch and the Wardrobe' opens on 8 December