Downton Abbey and Twenty Twelve star Hugh Bonneville takes the lead role in Mr Stink...

Hi Hugh. Tell us about your character, Mr Stink?

Mr Stink isn't entirely sure why people call him that. But they have done over the years and it's stuck. And stunk.

On first meeting he's a curmudgeon, which conceals a great deal of melancholy. We discover later on in the story that he's trying to keep the world at arm's length due to a tragedy in the past. He shields himself from the real world by encouraging a smokescreen of smell around him so that people don't get too close, literally and figuratively.

Were you already familiar with David Walliams' children's books?

This is the first of David's books that I've read and I love it. It's contemporary, funny, rude, full of smelly jokes but also touching and thought provoking. David has done the adaptation with Simon Nye and it's a gloriously funny and warm script, perfect family viewing for the Sunday before Christmas.

Did the make-up and costume transformation take a long time?

I think Kate Benton, the make-up designer on the show, has done a fantastic job. We spent a couple of days before filming trying to get the look right. We wanted it to be our own take on the character while retaining a flavour of Quentin Blake's fabulous illustrations in the book.

I think we got the transformation down to ninety minutes in the end, with all the gunge. We have different levels of gunk in his nails and all sorts of smelly horrors living in his beard. Bits of my beard were shaved off to accommodate these nasty bits of whiffy splodge, so when not filming I sensed people's eyes drifting to the strange patches in my face!

Over the last three years it's become a bit of a tradition with me to grow a beard after six months of Downton and having to shave at 5am. I can't stand shaving, so going native for a bit is a great relief. But Mr Stink's beard was enormous by the end, so in fact shaving it off was itself a nice change. The beard has served me well though - a pirate in Doctor Who and now Mr Stink
. How have members of the public reacted when they've seen you shooting Mr Stink?

Well a few people have joked 'oh you've fallen on hard times Lord Grantham!' But it was interesting when in costume, in the street. There's no question that people look at you differently. Very differently.

Have you had to do anything unusual for the role?

Yes, it's the first and hopefully last time that I have ever had to bath in a pond. The other first was being a barista, albeit an eccentric one. Mr Stink's smell clears coffee shops, leaving him in peace to concoct his own special drinks. That was fun. And so was shouting rude things out of a stretch limo on our way to meet the Prime Minister.

Have you enjoyed working with Britain's Got Talent star Pudsey, who plays Mr Stink's dog Duchess?

We got on famously once he had grown used to me. I fact he got a bit nervous when he saw me out of costume one day - but once I got into my smelly big coat he was quite content again. His relationship with Ashleigh is just adorable. He's a lovely well behaved dog, who clearly didn't mind dressing up as a Laydee.

At home I have a Tibetan terrier. I'm still not sure if he's a genius or very thick. It's a fine line. He's certainly not as acrobatic as Pudsey.

Is there a message to Mr Stink?

There is a very simple one, be kind to those less fortunate than yourself. There's also a lesson for parents, about allowing their children to breathe and their imaginations to flourish at their own pace and in the direction they choose. Mr Stink's influence on Chloe is to allow a girl who feels she's an outsider, in the way that he feels he is an outsider, to feel loved. Mr Stink ends up feeling loved, even though he's not very good at expressing that. He moves on to the next stage of his journey through life feeling hopeful. It's about compassion really, underneath all the poo jokes.

Mr Stink will be shown over Christmas. What's a typical Christmas in the Bonneville household?

A typical Christmas is me shucking oysters. I love them and I always get them in at Christmas. The number of yelps and cries for bandages as I prise the shell apart have decreased over the years - I'm getting quite good at opening them these days. But that's pretty much my role for the day as I am a complete liability in the kitchen. However, I'm quite good at opening wine. And drinking it. Hopefully not before the extended family has arrived; there are a lot of them and they're always thirsty.