What appears from the outset as another well-meaning and robust artist bio-documentary which offers a whistle-stop tour through a life lived at the vanguard of creative expression, is actually a fairly sad film about a daughter reflecting on the complex relationship she had with her late mother.

The daughter in question is the croaky-voiced Celeste Bell, while the mother is Poly Styrene (aka Marianne Elliott-Said), erstwhile lead singer of ’80s alt pop-punk outfit X-Ray Spex. As we take in episodes from Poly’s tumultuous life and career, we also receive a commentary from Celeste on how these moments add to a more lucid portrait of her louche rebellious ma.

The Brixton-born Poly Styrene burst onto the London punk scene from out of nowhere, and due to her unique fashion sense (antiquated charity shop threads, eye-popping colours, tram-line braces on her teeth) and a booming set of pipes, was embraced wholeheartedly as an alternative to the ubiquitous white male oik. The film contains passages of Poly’s own writings, intoned by Ruth Negga and given an extra sheen of vintage authenticity by being played back over a scratchy tape recorder.

A host of friends and acquaintances are on hand to flesh out the picture and offer their own reminisces, the most evocative being one from Don Letts who details the strange machinations at a house party hosted by the Sex Pistols, which included Poly heading for a lengthy trip to the bathroom for an ad hoc image change. Indeed, this moment also acts as a pivot point in the narrative, as those around Poly started to believe she’s suffering from mental illness and there were attempts to have her sectioned.

The film doesn’t put too fine a point on the urgency of the music and allows the energetic performance footage to do much of the talking on that front. The band’s lyrics were simple and direct, often used as a way for Poly to express confusion about her race and identity. There’s perhaps the suggestion that it was her impulsiveness as an artist, as well as an unwillingness to conform to corporate box-ticking, that prevented her and the band from becoming even more of a success outside of the interior-looking punk scene.

As her music career seemingly wraps up with half-an-hour still on the clock, the focus too shifts to exploring her successes and failures (mainly failures) as a mother. In a monologue at the beginning of the film, Celeste expresses trepidation at the prospect of digging into her mother’s private archive, and when you see how badly she was treated as a toddler, you understand straight away why.

This is a very worthwhile film specifically about a woman’s sour lot in the music industry, and the fact that Poly remains appealing despite her antisocial tendencies is down the the careful tonal balance that the film strikes.