WHEN your cheating partner waltzes off with your boss and you are left looking like an idiot, the idea of all three of you working together again seems like rubbing your nose in it.

But Michael Sheen is clearly one to forgive and forget.

Why else would the Welsh actor have made a movie with his ex, Hollywood star Kate Beckinsale, and the man she went off with, director Len Wiseman?

Ironically, the three were reunited for Underworld: Evolution - the sequel to the hit vampire movie that was responsible for their worlds colliding in the first place.

Three years ago, Kate was besotted with Michael - her partner of almost a decade and the father of her three-year-old daughter Lily. She even begged Wiseman to give him a part in her latest movie, Underworld.

But during shooting, Kate fell for Wiseman - who was married at the time - right under Michael's nose. And afterwards they both unceremoniously dumped their other halves so they could be together.

It was all very messy. Yet if there is any lasting bitterness or animosity it wasn't evident making the sequel. To complete the happy family picture, Lily, who is now six, also got a small part in it.

Kate, the 32-year-old daughter of late Porridge star Richard Beckinsale, insists there was no awkwardness on set, and says they have all remained on good terms for Lily's sake.

"We're very lucky," she says. "It's one thing that we have all worked very hard at to make sure it's a very good experience for all of us and for Lily.
"I spent nearly 10 years of my life with Michael. I don't think I've got horrible taste and I really value the friendship I have with him, and the fact that he's Lily's dad.
"I don't see how you could spend all your 20s with somebody and end up hating them. Certainly not in my life. Whether the relationship is right or wrong, it doesn't mean there can't be a relationship - we feel very modern and groovy about it."

Kate says she knew she was going to marry Wiseman five minutes after he first kissed her. He must have felt the same way, because soon after Underworld was released he divorced his wife and proposed to Kate. She ditched Sheen and took Lily to Los Angeles to be with Wiseman - a move which shocked her friends back in London.

"There was never anything interesting about me before," she shrugs. "I was with the same guy throughout my 20s, I had a baby and stayed home a lot. I'd never been drunk, never dated anybody famous."

She married Wiseman in May 2004 at a Los Angeles hotel and they set up home together in Venice Beach, California. Sheen lives just a short distance away in Santa Monica and sees Lily whenever he wants to.

"Lily's father and I separated when she was just three, so I think her conscious memory is of always having had two fathers," says Kate.
"We were very lucky in that we didn't have an acrimonious split. We are still very close and she sees us around each other. She's around them both at the same time and it's not at all weird.
"From what I can gather from her she feels very lucky to have two fathers and is a bit sorry for the children who only have one."

IF there was any embarrassment when Kate reprised the role of vampire heroine Selene in Underworld: Evolution, it wasn't about co-starring with her ex.

She had to do a graphic sex scene with Scott Speedman, during which he had a problem with his, er, manhood.

"I felt so much better about the scene because Scott was in hell because he has moveable parts," she grins.
"For a man, a love scene is much more intimidating because, you know, if it moves around then it's embarrassing, but if it doesn't move around it's kind of insulting. There's the dilemma of what to do with it.
"In the end I think he tied it to his leg but he tied it too tightly and it hurt. So he was preoccupied with the physical pain he was in... Scott had a hard time."

It wasn't exactly easy on her husband, either.

"It was tortuous," Len recalls. "To see your wife in a love scene with another man is agonising."

Although her home is now in the States, Kate confesses she misses life in Britain. She loves popping back to London to see her mother, the actress Judy Loe, and her stepfather, director Roy Battersby.

She will be soon be spending even more time in the capital. She has just bought a house there and plans to use it as a base for six months while appearing in a play.

One problem with that, though, is how her American-born husband will overcome the language barrier.

"He's very American and the first few times I brought him to England to see my parents I thought he was awfully quiet and very thoughtful," she says. "Then I realised he just didn't understand a word anybody was saying.
"Back here I get a strong English accent and talk very quickly with in jokes about TV programmes and things - he's just clueless.
"So we bought him a T-shirt that said 'I Have Absolutely No Idea What You're Talking About' and he wore it all the time. We also made him go to a pantomime which confused him totally, and then bought him a book of Cockney rhyming slang - so I think he's happy to be back home in California."

Their careers involve spending time apart, which has led to speculation that their marriage is in trouble - something Kate denies.

"I think it's because other people are a tiny bit more calculated and go to more events and kiss and stuff," she says. "We've been working and staying at home with our kid.
"Having a child changed my life. I have no idea what it would be like in this business without the sort of levelling that having a kid brings.
"I had her young and none of my friends had babies until this year, so I'm just cackling. My child sleeps, my child goes to the bathroom by herself... I feel spoiled that I have this little person who doesn't wake me up and throw up on me in the night."

Since making her US breakthrough in wartime drama Pearl Harbor, Kate has barely stopped for breath. She appeared in the horror thriller Van Helsing and played Ava Gardner in the Oscar-nominated The Aviator. She has just finished filming Click, a comedy with Adam Sandler, and is soon to start work on the drama Snow Angels.

When she does get some time to herself, her big plan is to finally learn to drive. She has already had some experience behind the wheel - mastering the controls of a golf cart.

"My daughter was very impressed," laughs Kate. "She said, 'Good for you, mummy. At least you're driving something.'"