Talking of which… how was it working with Sam on Revolutionary Road?

It was really, really amazing. Honestly! I would sometimes look at him with other actors and think, “God, that is so clever”. He was quietly getting them to tap into something they weren’t planning on doing.

He would do it with me as well. He’d turn us all inside out. April feels so trapped. It’s painful to watch…

With April, her interior world is so much bigger and so much deeper than her exterior world, and of course the great tragedy of it is the parameters of her life never allow her to indulge in her deepest emotions.

That was the thing about April Wheeler that touched me so deeply. And I’m so different to her: I’m a happy, positive person, and if something isn’t working I don’t sit around and go [adopts plaintive tone], “Oh, maybe...” I just go, “Right, fuck it…” and I change things, sort it out.

Is it true that Sam treated you like any other leading lady… even when you got home?

The big adjustment that Sam had to make was realising that I take my work home with me, I really do. I just can’t let things go whereas Sam is really good at compartmentalising.

We’d get home and as soon as we walked in the door I’d say, “Oh my god, I’m so glad you said that thing…” and he’d say, “Whoa, babe, hang on, let me have a cup of tea!” and I’d literally wait for him to finish his tea and then I’d say, “Anyway, and another thing…” And it would go on.

Wasn’t there a worry in you and Sam taking on this material together? Examining a marriage in such unforgiving detail?

I think it was great for us because you can never know enough about the person you’re married to. Honesty is everything in a marriage, and we’ve always had that.

It didn’t have any negative impact on us as a couple. On a very basic level, it was just amazing to have so much time together. We got to see each other every day for three months! And it’s kind of sexy, too, to see each other really stepping up to the plate, being good at what we do.