Let’s talk about nudity. it’s brought up in every interview and you must be sick of it…

A little bit. But go for it.

Well, let’s approach it in from a new angle, try to make it fresh for you…

Oh my god, that’s exciting!

It’s obvious you take your clothes off if and when you feel it’s necessary. You seek the truth. So what do you make of actors who have no-nudity clauses?

Isn’t that ridiculous? Everybody’s different and each to their own. I can’t judge. But, for me, I have absolutely gained from playing characters who take their clothes off.

I have gained being able to penetrate… [Pulls face, puts on a comically musing tone] interesting use of word, maybe we won’t use that word… I have been able to… understand those characters in a much more profound way. Some people say it’s unnecessary but of course it’s necessary.

It adds layers to who those people are as human beings. And for me acting is about being honest – not hiding behind anything. I can’t be dealing with the unspoken, in any part of my life.

Does the nudity get easier the more you do it?

The scenes don’t get easier. Because there’s always a scene going on, a performance to think about – it’s never nudity for the sake of nudity. But the physical act of taking my clothes off on film, in a roomful of people?

That gets easier because I’m used to it. And after you’ve had kids and you’ve been in that delivery ward… frankly? Goodbye vanity, goodbye self-consciousness! [Grins]

I’m not embarrassed about my body. I’m not. And the real me – the really, really real me – is something only my husband will ever see, because yes, there I am naked on screen, but it’s lovely lighting and you’ve got a bit of body make-up…

Of course, everything must seem easy after the urination scene in Holy Smoke…

I can’t believe I did that! How the hell did I have the courage to do that? [Laughs] That was really ballsy.

Would you have gone for it if Jane Campion had said, “Sod the tube, I want you to really piss yourself on camera…”

We tried! Belieeeve me we tried, we tried for the wee! We camera-tested the wee. But the reason it didn’t work was… [Stands up and plants feet firmly apart] if you’re a woman and you stand like this and you wee, it doesn’t go in a nice stream like it does for a bloke.

[Indicates an untrammelled gush] It goes all down the leg! It didn’t work for the shot. So we faked it and it was pretty funny.

The make-up artist got a bag and attached it by a wire to the back of my hair; it dangled down and sat in the middle of my back, and then it was pierced with a bit of surgical tube which went down, wedged in my bum crack, and I then had to wedge it [mimes pulling the tube up through her legs]…

Basically I had to wedge it by my wee-wee bits. Can you imagine getting ready for the scene? I mean, we were in hysterics!

I’m literally going, “Can anyone see the tube?” And they’re like [leans forward, acting out an inspection], “No, no, you’re fine.” “Really? Even when I walk? Watch when I walk…” [Waddles forward and then re-enacts the frenzied inspection] “No, we can’t.” it was absolutely mad.

Interview by Jamie Graham