The sex scenes were a particular challenge for the technical team, briefed by Fincher to make the actors look like “one of the statues at Mount Rushmore fucking the Statue Of Liberty."

"It was as if you had these two giant monuments fucking each other and you can sort of fly around them with a helicopter, that was kind of the idea. It was kind of inspired by Francis Bacon. This idea of the twisted perversion of flesh.”

Shooting them was resolutely unsexy, however.

“It was really weird,” says Bonham Carter. “Because me and Brad had to spend a whole day virtually naked, which wasn’t bad I guess, with dots all over ourselves, like little stickers."

"He had white dots and I had black dots and we had to assume  different positions in a very overlit studio and be surrounded by all of these still cameras. Fincher would just say, ‘And... Have sex! Okay. And orgasm!’ It was just completely absurd, but Brad was very chivalrous.”

"And then there were the off-camera sound effects. “That was just HBC and I sitting in a room  screaming our guts out,” says Pitt. “The sad thing is we had no qualms about it, no politeness, no little hint of embarrassment – just go!”   

“One of the studio’s issues with the material was how we were going to handle the sex between Marla and Tyler,” says Fincher, whose trade-off for the studio shelling out on Pitt’s dentistry (they paid for the removable cap that ensured Tyler could have a chipped tooth) was that the star would sometimes take his shirt off."

He did it twice. One of which was when he opens the door after sex with Marla – wearing a rubber glove.

“We had that take starred and sent over to Fox under the guise of, ‘Look! Look how good he looks, he has his shirt off!’” laughs Fincher.

“I’ve learned that one way to control people is to give them other things to worry about. If you’re worried that somebody is too fearful you can either try to empower them or you can give them so much to fear that they just don’t want to be around you. Either way you’ve sort of neutralised them!”

The biggest concern of the studio, though, was not the sex, or the violence, but one line: when Marla lies back in bed with Tyler and says – and this makes even Tyler shudder – “I want to have your abortion.”

“I always thought it was a good line and it made people uncomfortable,” recalls Fincher.

“But they didn’t want to get into the whole Religious Right thing. I mean, this movie is the poster child for movies that should be picketed. And Laura [Ziskin, president of Fox 2000] begged me, ‘Please come up with something else.’”

Fincher agreed, but only on condition he wouldn’t have to change it again. Then Ziskin heard the changed line (“I haven’t been fucked like that since grade school”).

“You know in ET,” says Fincher, gleefully. “When his head extends up on his neck? Laura did the inverse. The first vertebrates in her neck just contracted wafer thin. She just cringed so hard.”

Next: Edward Norton