David Walliams: How I created a Christmas stink The biggest pitfall in adapting is trying to do it straight from the book. After the first few drafts, where you follow the book, you start inventing things that aren't in the text, but are thematically correct. Those are the bits you love the most. I had to tone down some of the wilder elements, and make the motivations of the characters watertight. I did really work on having more suspense. I didn't want the film to be kidsy. I wanted more jokes that were going to appeal to a family audience. You can do more subtle things - Hugh Bonneville, who plays Mr Stink, brought in a lot of moments that weren't in the book. When he's saying goodbye to Chloe at the end, he smells her clean hair and thinks it's disgusting. I watched that and thought it was brilliant. It's great when you see the actors adding something that you haven't thought of. I kept my distance during filming. You have to trust the director and the producer, and the actors, and not be an irritant. But you do feel like a magician when you've written something. I went to visit the set and I saw the snow on the ground when Mr Stink leaves, and I couldn't believe how beautiful it looked. I really wanted to cry. My wife said she's only seen me cry twice: in Billy Elliot the movie, and Billy Elliot the stage show. I only cry when I watch Billy Elliot. Though when I heard Hugh read Mr Stink through for the first time, I had tears in my eyes. Hugh is a very subtle actor, and has an innocence about him. Nell Tiger Free (great name), who plays Chloe, has one of those faces where you really care for her. And there's Pudsey, from Britain's Got Talent, in it too. I'd often tease Hugh and say that Pudsey was getting top billing. People were always more excited to see Pudsey. So Hugh got used to feeling like the dog was the star. The great Quentin Blake, who illustrated the book, is doing the opening titles of the film. When you see Hugh in his tramp costume, he looks very much like how Quentin's drawn Mr Stink. The film has a hyper-real quality, which comes across in the special effects - like my favourite, Mr Stink's actual smell, which looks good in 3D. I don't think you can create a character without a part of you being in them. I relate to Chloe, but I can also imagine being the dad hiding in the cupboard under the stairs because I didn't want to tell my wife I'd lost my job. I can imagine putting my ambition before everything else, like the politician mother does in her quest for power. I can imagine being as lost as Mr Stink is. And the wicked characters get redeemed - I think there's good in everybody. Even dictators still probably read to their kids at night. The emotional scenes are the ones I'm looking forward to most. That's something I've never presented before on screen. Because the film's about treating other people in a kind way, and that's something that we're reminded of at Christmas. And I love the idea that people are going to sit there on Christmas Day, brought together as a family, and have a little cry together. Mr Stink is on BBC One on Sunday at 6.30pm