Puttnam said that the film, which won four Oscars in 1982, including Best Picture, only became really successful at the Box Office during its fifth week in the cinema.
"That couldn't happen nowadays - literally couldn't happen - no one would wait that long," he told London Live. "So there's an example of a film that honestly would have vanished."
One of the problems, he suggested, was that there are "almost too many movies struggling for too little screen time." The producer was talking to London Live's Luke Blackall at the Luminous gala dinner at the Guildhall, held to raise money for the BFI's film archive.