Then it turned out to be the first film I saw in Dolby stereo. I knew an immense amount of time was taken in post-production to give it that off-world sound that you find even more in Blade Runner, the film Ridley Scott made after Alien. It was just lovely to hear the sound of next-millennium machinery in space. It had a real texture to it.
Every science-fiction film that has come after it seems to have that gritty, grimy, wet, steamy look, that kind of blue light and green darkness. It has totally changed the genre, when you consider that only two or three years previously Star Wars was it as far as sci-fi was concerned. And the look has stuck; it's even seeping down into Star Trek: The Next Generation. Without doubt, it has to be the most influential film of my life.
There's one scene in particular of which I thought: I wish I'd shot that. They're hunting down the alien after it's come out of John Hurt's chest - they believe it's only the size of a small hen at that point. They send Harry Dean Stanton off on his own to look for the ship's cat, and we all know that in the meantime the alien has got a lot bigger . . .
The bit that for me was real cinema is where Harry Dean Stanton is leaning down to get the cat, and the alien's tail just sweeps down into shot. It's like ballet. And it's so understated: you know just from the tail that this creature has immense power and is going to get him.
It was so minimalist, so un- gory. The audience knows something bad is going to happen and everyone is expecting the alien to jump into the shot in some way, but it does the opposite, it slowly and majestically moves in. It's a real shame because whenever they show Alien on television you miss it because it's right on the edge of the wide screen.
It's the first time I'd ever seen on film a creature that was a true predator. It's purely a mechanical effect, nothing that couldn't have been done previously with just a little applied mechanical engineering knowledge: there's no Jurassic Park- style computer graphics. But up until then, whenever I saw a movie monster, it would be a guy in a rubber suit shuffling into shot; it would always have that staged feeling about it. Or the film-maker would rely on editing but you would never really see the creature. However, in this sequence the alien moved like a cat that was stalking, and we could see it even though we couldn't quite make out what it was, which added to the terror. That in itself was very interesting.
One of the other things that's really nice is the teeth of the alien: it seemed to have so many. When it opened its mouth there was another mouth inside it - which was a genius stroke. Carlo Rambaldi, who also did E T , produced the working model for the alien. And H R Giger's design is genuinely shocking and surreal. I think 70 per cent of Alien's success is owed to him.
Ridley Scott realised that, no matter good your special effects are, if you leave them too long on screen, people will spot that they're not real - even Jurassic Park doesn't ever linger on the dinosaurs. H R Giger actually complained to Twentieth Century Fox that all the best shots of the alien were eventually cut out of the film. That may be true but I also think that, if it hadn't been, in many of the shots you would have seen the zipper on the back of the suit. Because that's what it is at the end of the day, even though they did have lots of animatronic add-ons: just a rubber suit with a guy in it.
Chris Jones' first feature film, 'White Angel', opens on 15 April
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