Richard Eyre on how to direct a Scandal...

When you first got approached, what attracted you to it? The book? Marber? Judi Dench?

I think it was a combination of all those things and also Cate was in the picture, plus the fact that, with Scott Rudin, films get made. And this may sound an extraordinarily banal to say, but there are very few producers who have projects and can get them made. If I hadn't been interested before, the fact that the project could actually be achieved is in itself very attractive. But, of course, the component elements were irresistible.

It was Scott's idea to cast Judi Dench as Barbara. Did you agree?

No, because I thought when he initially mentioned it to me, we had just done Iris, Scott was one of the producers of Iris. So he was thinking, "Wouldn't it be great to find another project for Judi Dench?" And it struck him and me when I first read the novel that she would be wonderful in the part.

So you'd thought of her as well?

I thought this might make a good film, but hadn't done anything about it.

Are you close to Judi outside of work?

I've known her for 30-odd years, so yes, we've been friends for a long time.

What did she say when you approached her?

She had read the novel and really, really liked the novel. She's always been attracted to doing things which people think she can't pull off. So if you say to Judi, "Here's a part for you but you're not really right for it," immediately she thinks, "Oh, this is something I've got to do!" Not that I did say that to her. But she tends to play people who are mostly good-hearted. She's a quite spectacularly generous, decent person, who radiates goodness; she's widely regarded as a secular saint, and rightly so!

And she's just wonderful company; a good, funny person. So it's an attractive idea to have her playing the complete opposite of everything that she is, someone who is malign and small hearted and mean spirited and desperate and obsessive. And I think for any actor it's a challenge. It's wonderful to be asked to play things that, on the face of it, seem improbable. And also she's got practically no vanity at all. She has a great deal of respect for her own talent. It takes a curious and rare form of lack of vanity to appear like that in a film. Dyed, reddish hair, shocking wig, fairly unflattering clothes, and somehow make that, not in any sense a sort of, "Look what I'm doing, I'm being that slightly Oscar-seeking… I'm playing somebody who is ugly, how brave!" but simply doing it because it's the truth of the character.

She shrinks into this very small, bitter, shrewish woman. She's not the person you'd think of playing a role like that - I thought of Helen Mirren when I read about it. What about Cate Blanchett? Was she attached early on?

Just about… she'd been approached, if not confirmed.

Did you think about anyone from the Iris cast, like Kate Winslet?

I didn't, actually. I think Kate was probably too young. Have you seen Little Children? Wonderful film. No, I didn't think of Kate, not least because she wasn't free! We all thought that if we could get Cate she was the world's best casting.

What about the kid? Andrew Simpson. What were you looking for in him?

We cast the net very wide. I guess we were naively thinking that the James Dean of North London would emerge! We thought we'd see two or three hundred boys and this boy would walk in and we'd think, there he is! Gary Oldman, Tim Roth! And we didn't. We didn't find him. We saw hundreds of boys. Screen tested a lot.

It became clearer and clearer that there's a huge difference between a 16-year-old and an 18-year-old and that the 18-year-olds couldn't really fake it. We so wanted a boy who appeared plausible as a 15-year-old, otherwise you could so easily slip into a Desperate Housewives, the boy mowing the lawn kind of sexy 17-year-old. He's a KID, not an adult.

And when you found him, was it a little bit of a process, or was it like, "Let's get him!"

I thought, "Here he is, let's get him!" And then we had to make sure. It's alright saying trust your instinct, but we still had to test him and make sure there aren't any others who were better than him. It was a pretty exhaustive process. He tested with Cate Blanchett as well.

Does the fact he's Irish have any significance in the script?

Not really. In the school in which we were filming, it would be completely unexceptional for the boy to be not from North London. There were kids there… there's a huge immigrant population: Serbians, Bulgarians, Eastern Europeans, Somalis, Sudanese, even a couple of Americans. Somebody who came in who was Irish wouldn't be completely implausible. Of course we were a bit anxious in case people couldn't understand a word he said, but surprisingly, in all the screenings in the States, there have been no complaints. Given that they always complain about British working class accents!

How about the fact he isn't a James Dean type?

He isn't, but I think that he's charming and alluring. He's got wonderful eyes. But no, he's not a sex bomb at all. Certainly in the novel - and Zoë was always insistent - that he wasn't this great stud.

And we were very concerned that it was open-ended in the sense that you didn't think, "Of course, if I was her I'd have fallen for him." And also, by casting Bill Nighy as the husband, you don't think. "Oh, I see, this is a desperate marriage and she's married to a man who's much older than her and she's tyrannised…" You actually thought, "He seems pretty good company, he's a good father…" You have to ask questions beyond that, much more in an existential territory. What is it? What kind of desperation and loneliness lies within her that she is casting around for a relationship that is outside her marriage?

On every single level she struggles: she's married to an older man, she falls under the spell of this strange woman and then she falls for this student…

And also, of course, that because of marrying young, she feels she's missed out on youth. So it's a desperate attempt to regain that.

She doesn't really seem to have friends… Is she as isolated as Judi Dench's character?

She is isolated; isolated within the marriage. And obviously the presence of these children who are being very demanding have soaked up her life.

What about shooting tricky scenes between Cate and Andrew?

Well, all credit to Cate, really. Shooting sex scenes is difficult in any circumstances. Maybe there are directors and actors to whom it's all perfectly matter-of-fact, but I think it's, by its nature, difficult stuff.

Contrary to popular belief, it's all scientifically done; you have to know what you're doing, you can't just wildly improvise. And even if you did, there's no guarantee that it would look convincing. It's an odd thing, because on the whole we don't get to observe other people having sex! So it's much more to do with the feelings between the two of them. Cate was brilliant as an actor in making you believe that she found him very sexy, and therefore making him sexy, and making their sex scene seem remarkably plausible.

How was it for him? Was he…

…terrified! (Laughs) He's a good boy. He was just very, very nervous. But she was quite wonderful with him.

And you were quite discrete shooting them; there wasn't a lot of skin or whatever. Was that because of his age?

Partly. There are restrictions on what you can show and get a certificate for because of showing a 15-year-old boy… the fact that he was 16 was neither here nor there, because if you're saying in the film that he's 15, then in probably at least 30 states in the US it's actually a criminal offence. So there aren't scenes where the two of them are naked and you're showing genitalia because of that. But also, I'm not sure it would have made it more plausible if you had. And the thing about sex outdoors, and what I wanted is the… It's like teenage sex, tearing at each other's clothes, but it's too cold to take your clothes off!

What about the relationship between Cate and Andrew - did you talk to anybody who'd been through that experience?

No, I don't think so. Cate always said that she didn't understand it. It wasn't a problem playing the part, but as a woman, she said, "I simply cannot understand a 35-year-old woman being attracted to a 15-year-old boy." Her job as an actress was convincing us that she felt passionate about it, and that's what actors do; she doesn't have to understand it or find 15-year-old boys attractive, she just has to convince us that the character finds him attractive.

I talked to a lot of teachers, and one school I went into, I was talking to the English class and they were 15, 16-year-olds, and they said, "What's the film about?" So I told them. And they were, "Wooooooah!" I said, "Do you think that's plausible?" and they said, "You bet!" It wasn't just the boys saying it! And I said, "What about the teachers?" And they said, "Oh yeah, I think Miss Henderson might…" So, you know, it's sort of part of the speculation.

When I spoke to Andrew, he hinted it might have happened at his school…

Well, 15-year-old boys, they think of nothing but sex! You know, that's… they're always talking about sex and speculating about teachers' sex lives.

Do you think society condemns a woman for doing that more than a man doing it?

I think there's more condemnation of men with 15-year-old girls. There's somehow more perception of abuse of authority, whereas in some sense, all men think, "Isn't that the fantasy of every 15-year-old boy?"

Because you don't necessarily think it's damaging for the boy.

I don't think it is.

But you condemn Barbara more for being so manipulative.

But also Barbara's quite clear-headed about it, when she says, "Do you think he's concerned with you." She's very scathing and probably quite accurate.

Are there any more developments with bringing Mary Poppins to the screen?

I don't know! There was some completely fictitious story about me having conversations with Steven Spielberg. I've never met him. I've never spoken to him in my life! To do it would be interesting, but I don't think… I don't know, actually! (Laughs) It's a Disney project, and the last thing that is likely to happen would be for Disney to go to Steven Spielberg, for a start, because he takes first dollar. And Disney, that's anathema to them.

Notes On A Scandal is released in cinemas nationwide on 2 February 2007...