Ms Kidman said she was persuaded by co-star Iain Glen to reveal all after the two made a pact that if one of them undressed for the play, then the other would as well.

Mr Glen felt nudity was essential for his part - so his co-star followed suit.

The pair were the only people on stage in the erotic comedy written by David Hare, which ran at the Donmar Warehouse theatre in Covent Garden.

Speaking to Vogue magazine, Kidman admits she was initially nervous about taking her clothes off, but insisted she stopped being aware of it once she got in front of the audience.

She said: "It was so embarrassing at first, but Iain and I had made a deal.

"He thought his character should be naked and I didn't think it was right that I kept my clothes on - although we didn't take them off until two days before the previews.

"Of course, in character, I'm not even aware of it."

Staying in London

Tom Cruise: Kidman besieged by photographers after he saved a neighbour

Kidman, 31, set up home in London with Tom Cruise while they were filming Stanley Kubrick's film Eyes Wide Shut, due for release in the summer.

Now they have no plans to move away, saying London provides a more peaceful life for her and their adopted children Isabella, five, and Conor, three.

She said: "I love living here. LA is much worse for us, with all those stalkerazzi everywhere."

She said she had attracted attention from British paparazzi - especially when Cruise hit the headlines when he saved a neighbour from muggers earlier this year.

But she added: "I'm not the kind of person who gets mobbed like Madonna. People do give you space here.

"I can take my kids to the park almost every day. I sit and talk to other mothers. I'm not a recluse.