It’s an intense, 86-minute pleasure to be in the company of Don Letts: DJ, film-maker, musician, social commentator and thoroughly engaging raconteur. Every word that comes out of his mouth is a manifesto for humanity and creativity. “Punk rock’s a living thing,” he says, “something to look forward to, not look back on.”

Letts became part of the punk scene in late-70s London, befriending everyone from Malcolm McLaren to Bob Marley; he was DJing at the Roxy in Covent Garden, and with his pioneering choice of reggae records, Letts almost single-handedly made allies of punk and Jamaican music and struck a powerful cultural blow against racism. He also, with his Super-8 camera, shot vivid and intense footage of bands including the Sex Pistols and the Clash playing live which has become an indispensable archival resource for anyone making films or TV programmes about punk. From there, he had a thriving career as a music video director, worked with Mick Jones to set up Big Audio Dynamite and carried on making feature films.

This movie retells the gripping story of a rebellious kid who actually set fire to his classroom desk (how many rock legends can claim anything comparable for their early years?) and became a cultural maven, someone restlessly, passionately interested in music and film. Letts is a brilliant entrepreneur, an inter-disciplinary artist and eloquent speaker about what life was like in the punk era, and despite his (correct) refusal to see things in these tiresomely nostalgist or sentimental terms, there is a pang in recognising the spark of that time. He is shown actually unwrapping a brand-new audiocassette to put into his tape deck; I thought you could only get those things on eBay, but no. Letts is an evangelist for musical possibility.

• Rebel Dread is released on 4 March in cinemas.