There's one thing you can guarantee: it will be a different thing that works for every script. Sometimes I'm really floundering, trying to remember how I did it last time. Mike Leigh, who has been using the same technique for years, says that every time he goes into the film the starting point is always different, and he'll never know what it will be till the first day of rehearsal. Sometimes it's just getting the laugh right, sometimes it's when you try on the costumes, and you think: oh, I understand.
A different script calls for different things. It always takes me a long time to get to know the part, and know the logic behind the words. I have to be with the script for quite a long time before things start to fall into place, before they become part of the character.
With Mike Leigh you get six months' preparation; you're so secure and sure of what you're doing, you know why everything is happening. It's weird to get back to using a script; somebody has written these words and I have to mould my character around them. You have to twist bits of your brain around the part, and make the logic of the words right for you.
I know some people plot the whole role - they work through the subtext, they work out where every beat falls. What works for me is knowing the character in an emotional sense. I wish I was more logical but it doesn't work for me like that. I need quite a lot of time; it's why I always worry when I'm doing more than one thing at a time. I hope that some sort of magic will kick in. And then sometimes it doesn't kick in, and I'm halfway through something and I think: God, I've no idea what I'm doing. I have to admit I'm terrified a lot of the time.
It's the oddest things that help - a newspaper article will suddenly give you an insight. Images in a newspaper, photos, writing as if you're in the mind of the character, hearing a particular tune - anything can help. With Persuasion I could throw myself into the time, go to the National Portrait Gallery, look at pictures. Sometimes there's just a glint in someone's eye that kind of lets you in. Or sometimes it's when I'm out and about, I'll overhear something, or see something in the street and think: that's brilliant. You're always clocking things and tucking them away in your mind for use at a later date.
With Desert Flower, a film about Waris Dirie, who spoke out about the subject of female genital mutilation, I didn't need to do so much background reading because my character, Marylin, doesn't have to know much about what's going on. Marylin, who becomes Waris's friend, has this living-in-a-bedsit, working-in-Topshop way of life, and her dream is to become a dancer. What I was trying to get at was the way this girl is clinging to a dream that doesn't make sense: she's not that great a dancer - which I think she knows - and yet still she clings on.
So I was rummaging around in her childhood, trying to work out where this dream had come from. It is a peculiar process. It's even odder when you have to say goodbye to a character. Sometimes it can take a long time to shake them off. It's taken a long time to say goodbye to Poppy [from Happy Go Lucky], for example. When we finished the film there was a sort of shedding of her skin, but then she came back with all the publicity [Happy Go Lucky won nine awards for Hawkins]. It's weird, it feels as if I miss them, but I feel that if I need to call on them at all, I could. They become like dead relatives, really close somehow.
It's different for every project. Some parts are quicker than others to get and know; sometimes right up until the last moment you're just praying that something will click. But you can only do a certain amount of work and then at some point you've got to think: OK, I'm just going to have to leap now. I wish I could pin it down. I wish I knew the secret.