'Our job was to peel away the Union Jack to reveal the swastika,' reflects Rock Against Racism founder Red Saunders in a film whose recollections from an intensely volatile time can be very hard to hear. Directed by Rubika Shah, White Riot is a patchwork of evocative, often impassioned archive footage married with present-day talking head reflections from the likes of Clash drummer Topper Headon and Matumbi's Dennis Bovell.

Formed in response to the rise of the National Front and what's described as the 'poison in rock music' – which included shocking, pro-fascist statements from the likes of Eric Clapton, Rod Stewart and, perhaps most sadly, David Bowie – Rock Against Racism was a cultural movement, active in the late 70s to early 80s. They're perhaps best remembered for a series of seminal gigs which brought black and white artists together on the bill, including X-Ray Spex, The Clash, Steel Pulse, Tom Robinson Band and Alien Kulture.

The gang's cut-and-paste approach to enacting change is endearing, with Saunders and co proudly talking us through the production process for their fanzine Temporary Hoarding, while the way they empower their young acolytes is touching. Their desire to harness the punk scene, in particular, as an active force for good was genius; they used their concerts and fanzines to get musicians to nail their colours to the anti-racist mast, hoping fans would follow suit.

If the movement's white founders are clearly deserving of praise for their sense of solidarity (and some of the threats they received for their efforts were truly chilling), the film is careful not to put them on too high a pedestal. As the ska singer Pauline Black slightly witheringly points out, this was white people finally waking up to what black people had been living with for years. Importantly, there are painful accounts of just what Rock Against Racism was standing up to, as black and Asian contributors detail their mistreatment by police, their fear of gangs of counter protestors, and their experience of everyday hate.

Given the mainstream nature of 70s racism, some of what's shown here does serve to emphasise how far we've come, but much still rings true. That the recent Black Lives Matters protests have attracted such numbers and gained international traction is encouraging. That they are so needed is another story. Indeed, as the sobering words that close this film remind us, 'the fight is far from over'.

Available to watch in cinemas and on demand from Fri 18 Sep.