In Little Eyolf Ibsen examines the deepest relationships within a family – primarily between a husband and wife and parent and child. And there are other interfering components, for instance, my character, a half sister who spends too much time with the family and is far too affectionate towards her half brother. It's about the breakdown of a family unit due to a lack of communication, and hidden desires that don't match up to reality. It's catastrophic what happens in the play but it's not so extreme that it's not normal. It's absolutely normal.

It's quite usual for husbands to feel that wives have been taken away by the birth of a child, but in this play it's the woman who feels her husband has been taken, and therefore she has very ugly feelings for their son. And she's all too aware of this very lovely, cheerful half sister who's always on the scene and prevents her being the focus of her husband's world. So it's a kind of post-natal depression made more complicated by other factors.

Samuel Adamson has remained very faithful to Ibsen, so the basic structure and relationships he presents are still intact. It's a fabulous play which doesn't need much changing, but the translations we've had up to this point have been a bit turgid. It's such a difficult play and it must be a nightmare to translate. It's so difficult to know what Ibsen's getting at, so translators inevitably end up taking something of a middle line. But Sam's been very bold with it and as a result I think he's made it much more performable. He's also really brought the sexual subtext up to the surface, to create a very raw and pulsating version as opposed to something that remains rather shrouded in Norwegian mist!

If critics of the play question the point of the adaptation, they have to remember that it's often a very good thing to transplant a play to a more familiar territory. Sam told me that the 1950s is as late as he could have set it. My character for example is 31, she's a teacher, and she's 'on the edge' – she either takes a husband or resigns herself to being single for life. That kind of dilemma doesn't really occur now. The 1950s brings it near enough to be familiar, but it's far enough away for there to be a few other issues that come into play.

The designer told me the other day that I have a very suitable face for the period. I asked what she meant, and she replied “well it's about fashion – if you look at the pictures of women in the magazine, they look like you”. Mine isn't the sort of face that adorns copies of Vogue now, but apparently I've got a face that fits the 1950s template! Brief Encounter was set in the 40s so I suppose it was an easy transition for me to make, though there are big differences between those two decades. I wear trousers in Mrs Affleck, which was unthinkable just ten years earlier.

I'm lucky to have worked in all the spaces at the National – they're all great but they're all difficult for different reasons. People think of the Cottesloe as 'the small one', but that's a bit of a lie. For a start it's not actually all that small and acoustically you have to work very hard. The Olivier is thrilling and there are times when you can feel like you're flying – like you've pedalled so hard and then you just freewheel. I think designers have a tough time there though because it's such a huge arena and you have to focus the space. The Lytellton is kind of the best of both worlds – it feels contained but then it is quite big. I'm glad Mrs Affleck is in the Cottesloe, it's absolutely the right venue for it.


Mrs Affleck, which is directed by Marianne Elliott, runs in rep at the NT Cottesloe until 29 April 2009.