Fifty years ago, the Black Country legends made Slade in Flame, about a band screwed by the music business. It tanked and almost finished them. Now, as it’s re-released, the film is being seen as a prescient gem
Kevin Macdonald and Sam Rice-Edwards’s spry study of the couple in early 70s New York is as much as jittery collage of the era’s culture as it is a revealing portrait