In The Affair, Ruth Wilson and Dominic West's characters' sex scenes were a key part of their affair. Ruth agreed: "They can’t be purely titillation. They need to move the story forward and the characters forward."

But she also wanted equality on set: "I have a big concern about how women have to provide the titillation because penises can’t be seen on screen but breasts can. It’s assumed that women will get their breasts out, and have to get their breasts out, and I balk at that. It’s unnecessary and it’s unfair. So I kept insisting, ‘Why have I always got to do the orgasm face? [...] Why is it always the woman who’s orgasming? Let’s analyse the male orgasm. Why aren’t we thinking about that a bit more?’"

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When Scarlett Johansson, 30, was asked by Barbara Walters how she makes her love-making scenes so realistic on film, she replied, "You have to be totally without judgment, and it’s sort of liberating".

"It’s challenging. You have to stay in the moment," she added.

The star has acted in sex scenes alongside Jonathan Rhys-Meyers in 2005 film Match Point and with Joseph Gordon-Levitt in Don Jon (pictured).

Reese Witherspoon's departure from her 'America's sweetheart' image continues in Wild - the real-life story of former drug addict Cheryl Strayed.

Of the film's sex scenes, Reese said: "'[They were], like, three per cent of the movie, but it took up a tremendous amount of fear in my mind because it's daunting."

In another interview, she revealed: "I didn't want to do any of it... I called Cheryl the day before and I was like, 'I have to do this scene in this alley and I'm having sex with two guys' and I'm like, 'Why did you do this?!'"

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Playing Sabina Spielrein in 2012's A Dangerous Method with Michael Fassbender was a role requiring bondage and spanking. And for Keira Knightley, some steadying shots of booze.

“We were both very nervous about those scenes because they’re not nice, and when we shot them I said to Michael, 'If you touch me I’m going to kill you.’ He said, 'Keira, you’re tied to the bed at the moment. I don’t think you’re in any position to say that,’” she has said. “We had a couple of shots of vodka before doing the scene and a couple of glasses of champagne afterwards.”

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Sex scenes are probably daunting enough, but rolling around with Leonardo DiCaprio could turn most into a quivering wreck. Not so Margot Robbie, who played Naomi Lapaglia in Wolf of Wall Street.

"I kind of pushed Leo's head to one side and told him he was in my light and he moved out of [it]," she said. "He was so incredulous that I had told him to get out of my light, and physically moved him out of the way, he was like, 'Did you really just do that?' I don't think anyone has told him to get out of their light in quite some time."

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The raw sex scene in 2001's Monster's Ball became infamous, and star Halle Berry admits she and co-star Billy Bob Thornton agreed to be "uninhibited" for it to work. "There was no real direction in the screenplay, it just had to be animalistic...

"We just went for it. We both agreed to be uninhibited with our bodies... We only had to do it one time, which is good, because you don't really want to have to go there that many times."

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The graphic oral sex scene with Ryan Gosling in Blue Valentine caused controversy, but Michelle Williams is proud of the impact it made. "I thought, 'I've never seen that before in a movie and I'm proud to be the first. Good on us for making that happen.' As the woman in the situation that was in question, I found absolutely nothing scandalous, tawdry or disgusting about it."

She did admit: “I don’t wake up and jump out of bed on that day! Although many women would.”

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2010's Love and Other Drugs meant a lot of naked time for Anne Hathaway, and she confessed to initial shyness.

"There is that revoltingly embarrassing moment when you have to take your clothes off in front of strangers... I thought, 'Okay, I'm going to be in control. I'm going to do everything properly, disrobe at the last minute, and in between shots get the clothes back on.' But then I found that every time I put my robe back on, it rubbed all the body makeup off and that added 20 minutes to filming. As with all things in life, the second you stop making it about you and you make it about everyone else, it just got, dare I say, fun."

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Chloë Sevigny's scene with Hilary Swank in Boys Don't Cry was carefully planned out, the actress has said. "It was choreographed like a fight. The director will talk you through, so it's, 'Bring your hand down her back...' things like that. Or they'll say, 'Now you both orgasm.' It's easier if someone is coaching you through it."

Chloe really did perform oral sex on her co-star and director, Vincent Gallo, in 2004's Brown Bunny, and in 2010, admitted it was a complicated situation, saying: "I'll probably have to go to therapy at some point."

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Natalie Portman campaigned for her good pal Mila Kunis to be cast in dark 2010 film Black Swan, but said later: “I didn’t really think through the fact that I was going to have to have sex with her in the movie.”

She added: “It was pretty awkward. I almost feel like it would be easier to do it with someone you didn’t know. But, having said that, it was great to have a friend there who we could laugh and make jokes and get over it together.”

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Mila Kunis also had sex scenes with Justin Timberlake for 2010 film Friends with Benefits and had a very odd fortnight with her co-star. “It’s very awkward. It just is,” Mila said. “He’s great. I mean, the truth is, we got to have very uncomfortable scenes for two weeks…

"There’s like 150 crew men watching and you see each other’s bits and pieces. The whole thing is just wrong.”

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Unlike many of our gallery stars, Kristen Wiig thought her sex scene was hilarious - although to be fair, it was with Jon Hamm in 2011 comedy Bridesmaids.

She said: "There's some good positions in there. Jon Hamm — pumpin' away. He was making his money that day. There was nothing hot about that scene. We weren't, like, looking into each other's eyes."

She added: "You’re half-naked being thrown around and we laughed more than we probably should have."

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Starring in a film called Sex Tape, out earlier this year, Cameron Diaz was probably prepared for some raunchy scenes. In fact, she's seemingly unfussed about baring all.

"It’s just a part of the role," she said in an interview. "So I did it. I mean you see everything."

However her extra confidence may have been down to some secret weapons. “We actually had modesty garments and basically what they are are pieces of nude material that are cut and placed strategically on parts that we’re not exposing," she revealed.

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As Sex and the City’s Samantha, Kim Cattrall was regularly onscreen naked. However at 50 she decided to cover up.

“You see me doing maybe a physical, a sexual act, but there’s no part of my body that is exposed.” She added: “I don’t consider these sex scenes, I consider them comedic opportunities because all of these romps that Samantha goes on are funny.”

Discussing Sex And The City 2, Kim revealed some of the stress of filming nude.

“While we were shooting, someone on the crew took a picture… I was lying on the table and saw a flash go off so I said, ‘Get the police!’”