As the Star Wars juggernaut slips into gear for another tilt at the action figure market and a generation’s childhood nostalgia in time for Christmas, it gets more unlikely to imagine George Lucas as ever having been a visionary director. A great director of a simple, classic narrative in a spectacular, evocative setting, yes, but not someone whose science fiction made him a seer.

Yet the view that George Lucas was, in fact, a visionary is what’s inspired long-serving Hackney agit-punk group Asian Dub Foundation to select one of his films as their latest live-scoring project. Not Star Wars itself (and god forbid, none of the later prequels he was in the chair for), but rather Lucas’ 1971 debut feature THX 1138; it will be their third and undoubtedly most accessible venture into live-scoring after tackling Mathieu Kassovitz’s La Haine in 2001 and Gillo Pontecorvo’s The Battle of Algiers in 2005.

‘I remembered that THX is quite sparse,’ says Steve ‘Chandrasonic’ Savale, speaking for the group, ‘and I had an idea that enhancing it with music might work. Plus the content is very relevant; it’s a science fiction film, but it deals with questions of surveillance, the way sex is used in a society, the use of psychotropic drugs. A lot of stuff that’s happening now. I first saw it in the early 90s on a film programme introduced by Alex Cox (the cult director of Repo Man; the programme was BBC2’s Moviedrome). And he slagged the film, actually. He said it’s not a great film because it’s so alien and unknowable and impenetrable that it doesn’t say much about today’s society – that science fiction should be a parody of or a metaphor for what’s going on today. I watched it and I thought he was wrong on that front, the fact that it was so alien was one of its strengths.’

The film bears much of the visual aesthetic of Star Wars, with sets bearing clean, brightly-lit metal and plastic lines, and characters clad in stark white or menacing black. Yet it’s an austere, unfriendly future, where the menial and enslaved humans are chemically-controlled by a fearsome legion of expressionless androids to suppress their sexual desire and independent thought. Robert Duvall’s titular THX 1138 attempts to escape to the world above, with the aid of his cellmate SEN 5241 (Donald Pleasance).

‘Lucas and Murch’s (Walter Murch, co-writer and celebrated sound designer) concept behind the film was that it was like an artefact from the future, like you were looking in on the 25th century,’ says Savale. ‘You wouldn’t know what the hell was going on, and I love that idea. It’s science fiction with a sense of realism, even though it’s really way out there. Just that basic idea that you as a viewer watching the 25th century would struggle to work out the logic and the morality of that society. It would look like a huge digital mess. That’s another amazingly prophetic element, the overload of bleeps and static … the world is like that now, a never-ending stream of digital information and sounds. They got that a hundred percent right.’

It wasn’t all that was accurate, he says. ‘The surveillance stuff, where all your details are contained in computers, every last detail; we’re getting there. Religious fundamentalism is actually quite a strong theme in the film, which I hadn’t quite recalled - the idea that there’s something wrong with sex. And the drugs as well, there’s this actually quite scary scene where the kids are walking round with syringes permanently in their arms. To me it conjures up the whole ADHD thing, where a kid just shouts too loud and they put him on Ritalin.’

Savale adores sci-fi, particularly the edgier and more exotic, intellectual strand he discovered while growing up. He devoured Philip K Dick’s work as a teenager, and loves films like Alphaville and La Jetée. Yet he thinks what was great about the genre has been planed off in its contemporary format by the way the real world has caught up with it.

‘I don’t think it’s necessarily part of a revolutionary movement, to show a film,’ he says, ‘but I think this is an interesting film to interpret. The greatest science fiction creators can look at a certain tendency now and see its logical extension. I always found that very interesting since I was a kid, and they do it full-on in THX. It’s almost like they’re taking every aspect of life in 1971 and projecting it to the power of 100. There’s consumerism and state control and religious fundamentalism and drugs and therapy and computing.’

Played by a live quartet, ADF’s live score echoes the original soundtrack of revered film composer Lalo Schifrin in places. ‘There are actually some brilliant electronic bits in the film itself,’ he says, ‘but I’m on a crusade to say that guitar, bass and drums can sound as futuristic as electronics. In a way it would be quite obvious to make it full of synth sounds and what have you, and obviously we use loops and samples and stuff, but I think it’s quite interesting to do it with guitar, bass and drums. I remember in 1987 the Sonic Youth album Sister was voted the best science fiction album of the year by the Philip K Dick society, so I’ve always referred to that. Guitars can sound as futuristic as synths, and I see myself as a kind of science fiction guitarist.’

Asian Dub Foundation play George Lucas’ THX 1138 begins at the Usher Hall, Edinburgh, Sat 17 Oct, then touring the country until Tue 27 Oct.

Asian Dub Foundation - Mindlock (THX 1138 Rescore)