'Harry Potter' star David Thewlis talks to Linda McGee about his latest role in 'The Boy in the Striped Pyjamas', describing the project as a "wonderful film" and praising his co-stars.

He also chats about the Irish weather, his love of Peter Kay DVDs and how much his daughter Gracie enjoys visiting film sets.

Linda McGee: How did you first get involved with this project? Had you read the book or were you just sent the script?
David Thewlis:
Yeah, I read the script first. It's not a very interesting story. My agent said: 'There's this great script'. She emailed it to me. I read it, although I read it on a PDF file. I didn't print it out so I was actually quite surprised. I was just pressing the button like that (gestures) and then I was like: 'Where's the rest of the script?'. That can't be it.

So that obviously attracted my attention. I was moved. I mean what you get from the actual finished film, I had that reading the script. If you had printed it out and were like: 'Aw, there's two pages left', but I expected another 30 pages. So that caught my attention and then when Mark offered me the part I then obviously read the book.

I thought it was a very good adaptation and then heard the cast. I thought Vera Farmiga is a very good actress, a very great actress, so I thought that was a definite bonus and you know, the risk with the whole thing was that the kids should be great and there's no way of knowing that until you shoot. It could have been really bad if Bruno had been not that good, the whole film could have failed. Or indeed Jack. Fortunately they were both fantastic, and Amber - really, really good actors. So I think that's the main success of the film, thank God.

LM: Your character has precious little redeeming features. How difficult was it for you to prepare yourself for the role?
Well, it was fascinating really. What I did was I read this (displays a copy of 'Commandant of Auschwitz: The Autobiography of Rudolf Hoess') - so Rudolf Hoess was the Commandant of Auschwitz. Now I'm not playing him because we don't actually say it's Auschwitz in the book but he had five children and, rather fortunately for me, he wrote this book. He was ordered to write an autobiography by the British in between his trial and his execution. So I'm like: 'My God, I didn't know such a book existed' when I was thinking how could I get my head around playing this part and I'm like :'Oh, 400 pages written, well 300, by a man who actually was this man', so then you know, and this is a shocking piece of writing, but it really obviously helped me understand this character.

He was a family man and in fact in Auschwitz the compound where he lived with his children, where he raised his children, was in direct sight of the crematoria, so closer than in our film, so his children could see where millions of children were being gassed.

So, for all our story isn't true, in fact stranger stories were true in this man's case. And in talks in the same pages describing the deaths of several children, where in one particular scene he talks about he then goes back to his wife and children. So that's all true. It all happened to this man and in other camps along the way, not just Auschwitz.

LM: The moments that your character shares with his children display a certain tenderness that initially doesn't seem possible. Was it difficult switching either element of his personality on or off?
With Vera Farmiga in the filmDF:
Well, I just thought that these men, they weren't hunchbacks, twirling their moustaches and coming home going: 'Arggh'. They were obviously loving people, they fell in love, had children and raised children and indeed there's footage of Hitler playing with his nieces and looking like a kindly man. If you just looked at that footage and take the uniform away and the context you'd think: 'There's a man playing with his children'. So they had those human emotions. Unfortunately, they had a deficiency in lots of other parts of their soul so I just thought to play it like you would play any other father but be aware that inside there's something more pernicious.

LM: Was there a particular scene in the film that shocked you immediately when you read the script for the first time?
Yeah, well I think the dinner scene was what really caught my attention in the script. I think that's when I thought that this was a wonderful film and a great, great part, so I think that's the turning point for that character when you really see the evil in him. You see the accusation just before that with the wife sort of challenging him on that and him losing it. I think in fact in what we shot, and it was cut, he actually goes over and shuts the door and then sits down again, where it's just that he should ignore that brutality. I think is a turning point in the film.

LM: In terms of the emotional investment that you have to make in such a movie, did you find it draining or even disturbing to be in a place where you could draw from to build this character?
I didn't find it draining, no. I found it disturbing in the research for it. I basically just didn't watch any TV or read anything apart from this (refers to book) and other books like it, and documents of that period... and documentaries. There's a wonderful BBC documentary called 'Auschwitz', which is a six-part series, which is fascinating. Whereas you can't really immerse in the character, you can't become the character as one might try to do with other parts or indeed reference your own life as to anyone you may know like this. Obviously I don't know anyone remotely like this... I do actually know two people who've killed people. I do, yeah. They're some old gangsters. Won't mention their names, otherwise they'd kill me.

Peter KaySo I just immersed myself in all the period and the history until that just had to become overwhelming and the whole world became black and white, and red. And it kind of got to me after a while and I just wanted to put on some comedy after that. After a few weeks I remember watching a Peter Kay DVD. I had it in my bag and I was like: 'You know what, I've just watched one too many documentaries'. And it was so horrific and I was having bad dreams... and I just got it out of my bag 'Peter Kay: Live in Blackpool' and I was like: 'I think I've researched this enough'. So yeah, it was draining emotionally but at the same time it wasn't really bad.

LM: Workwise, when you finish a movie as intense as this do you like to look at scripts for much lighter projects?
I usually go and take a break but I didn't actually take a break. I went on straight to do this thing called 'The Street' for the BBC after that, which was quite harrowing as well, playing a man whose brother dies and he takes over his brother's life. In fact it was more harrowing. And then I didn't do anything for a while.

I'd like to be in a position where I can choose but you take what comes sometimes. I'm not getting so many scripts that I'm picking and choosing. The right things come along at the right time and I don't like to be away from my family a lot. We're living in America right now so I choose it do with that really.

LM: So you're living in the US full-time now?
Yeah, at the moment. We're living in Los Angeles for the foreseeable future.

LM: I'm sure you're finding the weather a bit more agreeable than over this side of the world? (the day after the premiere is one of the wettest days we've had all year)
Great, yeah. I lost my suitcase yesterday. It's alright, it's turned up now, but I has lost my suitcase and so for last night's premiere I thought: 'I need a new shirt', so I just walked down there and found this shop and I went in there. So I went down the street with a jumper on and I walked into this store and the guy was like: 'Hot today, isn't it sir?' (does an impressive Irish accent) and I was like: 'What?!'. It's not my idea of hot! But yeah, a bonus of living there is it's pretty sunny.

LM: Younger audiences will know you from your role as Remus Lupin in the 'Harry Potter' movies. Is it fun to be involved in something like that? It's definitely a project that your daughter will appreciate, I'm sure?
Thewlis with his partner Anna Friel and daughter GracieDF:
Yeah, well, it's gonna be great when Gracie gets old enough to appreciate that. She has watched it actually. She's already watched it and just thinks it's normal, even when I turn into a wolf, which is weird. I think she's been on so many film sets since she was born, because Anna (Friel) and I have just been working the whole time - and the last thing that Anna did, she did this film with Will Ferrell called 'Land of the Lost', which is all about dinosaurs and big lizard creatures, and when it was 'cut' they took their heads off and they're all talking to her and I've got these lovely photos of Gracie talking to these people in lizard suits. When she sees anything now sort of scary she's like: 'It's just acting. I'm not scared. That's acting. It's men in suits.' She saw a bit of 'King Kong' the other day and she was like 'It's not a real monkey, it's a man in a suit.'