In reply to Simon Caldwell:
> This was released on LP in 1957, but I would be surprised if there weren't something else earlier that decade.
The Forbidden Planet (1956) was, I believe, the first feature film with a wholly electronic score. (Shakespeare in space, Robbie the robot, monsters from the id etc., cracking film!)
I don't suppose they did, but if any of the sound track was released as a record that might qualify?
The score was quite Stockhausen-y iirc, but with the addition of a fair bit of noodling on a Theremin.