Emma Thompson is Nanny McPhee

The Oscar winning actress dons the make-up to play opposite Colin Firth in the upcoming film

Looking at Emma Thompson, you'd never think she could not look beautiful. But, if you've seen the trailers for her new film, Nanny McPhee, you may not even recognize her. In fact, I was one of those people who didn't know it was Emma as the wart-filled magical nanny.

When I spoke with Emma about her character, I told her that I didn't know it was her. Her reaction was one of happiness; she was glad I didn't recognize her. But I was still wondering why she would make herself look like that.

I was especially curious because she's also the screen writer of the film. Emma's answer was honest – she wanted to. 'It was a very difficult film to write and a very difficult film to produce, but it was just a kind of relief or something seeing this character who had nothing to do with me at all.'

When you see the film, you'll find out very quickly the stars of this film are the children – 7 to be exact. Emma had some good stories about the make up to go with playing Nanny McPhee, one involving the first time she walked on set. 'The children didn't know that it was me. We just said 'Nanny McPhee is here.' I would walk in and they were like, 'Huh. Nanny.' I said 'Hello. What are you doing? What's your name?' It was rather formal and well behaved and then one of the little ones said 'What have you done with Emma?' I said 'I've had her killed.' Then they knew it was me. They knew that no grownup would ever say anything so terrible about me. So they knew me well by then. They said 'It's you.'

Three of the kids were at the press day as well, and they, too, had some good stories about Emma in her Nanny McPhee make up. A name you'll soon be hearing about is Sam Honywood; he plays Sebastien, one of the youngest children. He's also probably the most mischievous of all the kids. He had a good reaction to Emma's stunt on the first day. 'Inside we were a bit scared but we knew that it wasn't actually a real person. She kept on saying she'd eaten Emma Thompson so she was quite heavy. I didn't like the nose; it was too round.'

There's a great food fight scene in the film; don't worry, that doesn't ruin anything. Actually, there are a few good food fight scenes, but one in particular was very memorable. Everyone had a chance to get in the action, even Colin Firth. 'I thought [it] was probably going to be a grueling experience because very often abandoned slapstick comedy isn't a particularly abandoned; it's going to look funny up there. But, it was great fun. Something that wasn't fun - the extraordinary popularity of the job of throwing the pie at the leading actor. I've noticed, not just on this film but on almost every job I've ever done, if something humiliating has to happen to me and any assistance is needed, the line of volunteers, and very often because rank was pulled in this, it was the director who actually was the one who actually threw the porridge, stood next to the camera and made sure that the pie/cake hit.'

Yes, Colin gets nailed a few times with pies, and other food. Emma had an opportunity to nail a legend in the scene – Angela Lansbury. 'I actually became very adept at throwing pies. The boy, the Box Boy didn't want to do it because it was too much of a responsibility and they thought that they'll hurt her and be fired and that'd be horrible. So I said, 'Okay.' I talked to him and I said, 'You can hit me. You can do what you want to me. I'll do it.' So I practiced with a lot of pies against a board and it was all going very well, and I was kneeling down in front of her behind the camera and she's sitting about where you are now and I lifted up my hand with the pie and I suddenly thought in my head, 'I can't do this. I'm going to miss.' So I handed over responsibility over to the pie. It was like Luke Skywalker with that thing where he got a hold of the Death Star. I just said, 'You have to make a pie that will go to the face. Use the force. Let the pie leave my hand and hit Angela's face.' And wham right there. One take. It's the most wonderful day in my life apart from giving birth. I'm not kidding.'

Those kids had way more fun throughout the film with food fights. It was their favorite part. The oldest of the seven children, Eliza, who's real name is Eliza Bennett, said it best. 'Yeah, the food fight was pretty good fun actually, because we had our costumes on all clean and everything and then we had big, huge plates of creamy cakes and we were allowed to throw them at a plain screen. And then, not knowing, halfway through the scene, Emma Thompson and everyone, other than the kids popped up with suits so they had protection with huge buckets of cakes and started throwing them back at us so it was really good fun because we were allowed to get messy and dirty.'

And who doesn't like to get messy and dirty! Well, maybe a certain donkey on set. Everyone we spoke to talked about how bad of an actor the four-legged animal was. Emma almost had to break a major rule; 'That donkey was supposed to be doing things and it just stood there as if it was injected with a half pound of heroin. You know that thing that's said at the end of movies where no animal was harmed accidentally or otherwise? I wanted to harm it. I wanted to have at the end of the film, 'Emma Thompson harmed this animal.' I had a real profound desire to hurt it.'

Colin wasn't too pleased with the donkey either. 'The film was fun except for the donkey; no one found the donkey fun. Donkeys are not fun animals when you want them to do things.'

As I said earlier, the screen play was written by Emma; the story is based on an old series of Nanny McPhee books. Emma took a lot of pride in bringing this story back into people's lives. 'I found it on the bookshelf and read it. I look at this strange dumpy woman on the front with these huge teeth and I was like, 'I think that I remember that book.' And I thought that there was something about this that would make a good film because visually that thing of someone changing is interesting and it being completely subliminal and so you're not sure why, and because film is so much to do with perfection and how differently you can feel about someone at the beginning of the film and the end of the film. I thought that something like this would be easy to adapt. Well, in fact it was more difficult because there's not in fact a narrative in the book. I suddenly discovered that I just agreed to write this and there wasn't a story. So I had to make a lot of it up really, and kill Mrs. Brown who was still alive and then kill a lot of the children because I couldn't have them. They had groups. My first version of this film had thirty five kids in it. Can you imagine? Clearly as the years went by they would kind of ground me down. They were like, 'You can't have that. It's too expensive. You can't do it.' I was like, 'Okay. Twenty nine.' Then I slowly went down to seventeen, thirteen, eleven, nine and I absolutely stopped at nine. I said, 'I'm not going any less than nine.' So that when I had nine there were two others and they were these sort of tomboy figures, but I realized I could not chart nine kids in an hour and a half.'

All the kids felt Emma made the right choice with seven, naturally. Most of the kids had never really acted before, so having Emma and Colin on set all the time was very helpful and a lot of fun. The most veteran of all the kid actors, Thomas Sangster, who plays Simon, talked about having them there. 'They're both experienced actors you can learn from both of them in different ways. Colin was fun but when he wanted to work, we'd get down to it. He'd really try and push himself to the limit and Emma was kind of similar as well. When she needs to act, she will put aside all the jokes and do what she needs to do so, in that way, they're kind of similar but when they say 'cut' it's back to the fun again.' Thomas can also be seen in Tristan and Isolde, as a young Tristan; and he also had worked with Emma before in Love Actually.

Nanny McPhee is a really cute and fun film for kids and adults. The children are great, and seeing Emma in that make up is worth the price of admission. But, honestly, it's a good story as well.

Nanny McPhee opens in theaters January 27th; it's rated PG.