The Lion, the Witch and the Wardrobe is the best known of The Chronicles of Narnia books. Is Prince Caspian a worthy successor?

On the page, it’s a less cinematic story than the first film because the Pevensies don’t meet Prince Caspian until halfway through the book, so we’ve made some slight changes in order to get them together sooner. But to me the key is hooking into the emotion of the story and one of the things I like a lot about Prince Caspian is this theme of letting go of past experiences and moving on. The Pevensies have had this experience in Narnia and in this story they come back expecting to relive it, but Narnia’s changed and they are forced to accept that.

And forced to accept that they are growing older too…

Exactly, because what I think CS Lewis was getting at was the transition from childhood to adulthood and the realisation that there are things you have to let go of. I related it to this experience I had when I was 11 years old and I moved to Papua New Guinea and I lived there until I was 18. I left and I’ve never been back and I know the country itself has changed drastically, so the place I grew up doesn’t really exist anymore, which must be what it feels like for the Pevensies.

You’ve talked about how nervous you felt going in to The Lion, the Witch and the Wardrobe because it was your first live action film. Is the second time a lot easier?

No, because I knew the challenges I would face on this film – all the things they warn you about, like working with animals and children and all the visual effects — whereas last time I was more of an innocent. Also, I feel like I’ve created new challenges on Prince Caspian to make myself just as nervous. The film got bigger for a start and it feels completely different. It’s obviously many of the same characters, but the characters have developed and, like we said, the world they are in is so changed. Prince Caspian is set 1,300 years later than the first film and Narnia is oppressed and the Narnians are being driven into the woods. It’s not the same thing at all. Beyond all that, things never go quite to plan on a live-action movie either, so there’s always some surprise around the corner.

Like what?

Well, the usual hassles of shooting with horses where you’re trying to get a close-up on a character and the horse won’t stand still. And we’ve had lots of problems with the weather. One of the reasons for not shooting the entire movie in New Zealand this time is that the weather is so unpredictable there, whereas the theory is that Europe is a big land mass and you can predict the weather much more easily. Well, boy, did we get that wrong! I think this has been the most unpredictable summer in Europe in living memory and we have gone from hail to sun to rain to fog and back to sun and back to rain all within one day. It’s been crazy, crazy weather.

Obviously one of the big points of interest in Prince Caspian is that you are introducing a major new character to the series: Prince Caspian himself. Did you spend a long time searching for the right actor for the role?

Oh yes, we looked all over, from Argentina to Italy, France, Spain, England, on and on. It was a difficult role to cast because I wanted someone that would integrate well within our family of actors, but our casting director saw Ben Barnes in a play in London and told me I had to meet him. So he flew to Los Angeles and I flew to Los Angeles, because that’s sort of halfway between England and New Zealand, and he just sold me. He completely understood the character, he had this love for the books and he so wanted to do this kind of film. And he’s been great! Ben’s older than Caspian is written in the book, but the other kids are older now as well, and he’s got a very youthful exuberance about him and he loves the horse riding and sword playing and all that kind of stuff.

You won’t be directing the next Narnia film. Is there any chance you will be back to direct any other installments?

There are four more and maybe by the time The Magician’s Nephew comes around, which is one of my favourites, I might be ready. But it will have to be a long while from now so I may be too old, but you know, never say never!