Thanks to BH for drawing attention to this, Ireland – A Television History from 1980 by Robert Kee. I remember it from the time. Well worth a look, particularly episodes 12 and 13 (links below). The footage speaks for itself, and viscerally most so, perhaps – counterintuitively – that from 1968/1969 before armed conflict had broken out. Mick Ryan is interviewed on the Border Campaign and unusually Danny Morrison for PSF interviewed in episode 13.