The scene:
Two puppets make the author of the Kama Sutra look dismally narrow-minded as they race through a mind-boggling array of positions. Sexual gymnastics have rarely looked so energetic. This is sweaty, hardcore marionette action. With strings attached.

The turn-on:
"Straight porn" is Hellyer's take on this notorious scene. This is the sort of wild monkey sex you'll only have if you shed all your inhibitions. And, if you're attempting the upside-down pile-driver, are in possession of a double-jointed penis.

"There's a lovely sense of abandon," Hellyer says of the action, "There are clothes and sheets everywhere." But she also points out that although the bedroom antics become increasingly demented, the build-up to the sex is textbook romance as the couple first lock lips before a spectacular mountain sunset. "It's a send-up of those clichés," concedes Hellyer, "But it's a send-up because these elements actually work."

Once the couple retire to the bedroom, the initial stages are also surprisingly tender. "They're going quite slowly at first," says Hellyer. "He lays her down gently on the bed while staring into her eyes. Then they get more adventurous."

Your sequel:
Prince memorably boasted about enjoying "23 positions in a one-night stand". But if you're not a pint-size pop legend, consider taking things a bit more slowly with a new partner. "When you're having sex with someone for the first time, a face-to-face position is good for the woman because she can see what you're doing," says Hellyer. "Positions when you can't see the guy's face can be a little bit unsettling."

Different positions have subtly different effects for women physically and psychologically. "If you're flat on your face as a woman, it's a slightly more submissive role; standing up might feel more adventurous," says Hellyer. "Doing something just a little different might make you feel wilder or more wanton or more loved. Experiment!"

Leaving aside the pile-driver for now, Hellyer reckons there are only six basic positions - woman on top, man on top, doggy-style, spooning, sitting and standing. "Then it's all about little variations," she says. "Rather than saying 'Okay, let's try Kama Sutra position No.63', try to allow the positions to evolve and flow." Sticking a pillow under your partner's hip can be an unobtrusive way to mix things up a bit in bed. "Whether she's on her front or on her back, it lifts up her pelvis to allow the guy to go in at a different angle, which will stimulate different things," explains Hellyer.

But when watching ambitious sex scenes, Hellyer stresses that you should always concentrate on the sensation rather then getting hung up on the visual spectacle. "Sex in the movies, whether it's erotica or porn, is designed to look good and turn the viewer on, but it doesn't necessarily feel good," she explains. "That's why you tend to see people doing the harder, faster, louder, rather than the more gentler, softer, barely moving stuff that can give you completely different but equally exquisite orgasms."