A maverick performer and cult figure who’s ploughed his own furrow for decades “in the face of commercial and critical indifference”? It’s not hard to see why Stewart Lee might regard Nightingales vocalist Robert Lloyd with admiration. But Lee leaves it to the audience of his film, a collaboration with Brass Eye director Michael Cumming, to draw the parallels between documentary maker and subject. Instead, he chooses to explicitly identify Lloyd with Nicholas Monro’s sculpture of King Kong, which stood unloved and vilified in Manzoni Gardens by New Street Station in Birmingham for eight months in 1972 before being sold off to a second-hand car salesman. The fates of these two giants, Lee argues, illustrate the fact that the city “seems to have a great history of rejecting its culture”.

King Rocker has been billed as telling the tale of The Nightingales, but in truth it’s much more a loose biography of the band’s frontman. Lloyd’s pathway to punk in the late 1970s was paved by familiar musical influences: Captain Beefheart, The Velvet Underground, Krautrock, an early Sex Pistols show. His band of scruffy upstarts The Prefects landed themselves a slot on The Clash’s White Riot tour, but it turned out to be a disillusioning experience – not least due to run-ins with the headliners’ manager Bernie Rhodes, who pompously referred to himself as “a patron of the arts” while branding them “amateur wankers” (a label they subsequently wore with pride). According to Paul Morley (contractually obliged to appear in all such documentaries, it seems), the short-lived band weren’t part of any scene or movement, and Lloyd and other members took that spirit of independence into their next project, more interested in Faust than in the cartoonish cliché of spiked hair and bondage trousers that punk had become.

The Nightingales went on to release three albums and, like their predecessors, were also championed by John Peel – but, as founder member Paul Apperly dryly puts it, “Everybody loved us except for people who bought records. That was a fucking drawback.” By 1986, Lloyd was increasingly distracted by the demands of running a label (Vindaloo, whose ‘office’ was the back room of a pub – Lloyd’s natural habitat) and sort-of-managing We’ve Got A Fuzzbox And We’re Going To Use It!!, and The Nightingales consequently fell by the wayside. His brief dalliance with a major label proved ill-fated when solo album Me And My Mouth flopped, and in the 1990s he went on to work as a video producer and a postman, trying his hand at creating a sitcom with the inimitable and combustible Steven Wells and (perhaps most improbably) replacing Nigel Slater as GQ’s resident food writer.

Lloyd’s move back to the West Midlands from London brought an 18-year hiatus to an end, with the reformed, reinvigorated and often excessively refreshed Nightingales once again entertaining modest crowds in poky venues up and down the country. Several personnel changes ensued (just one of the reasons they’re often mentioned in the same breath as The Fall), but the current lineup – Lloyd, James Smith, Andreas Schmid and Fliss Kitson – has a surprising air of stability and permanence about it. Drummer Kitson in particular has brought a measure of discipline and organisation on and off stage, with everyone (Lloyd included) following her beat. Noting her passion for taxidermy, Lee asks with a smile: “Do you think you’ve got a particular interest in preserving things that might otherwise have rotted away?”

King Rocker’s very existence makes clear he’s in no doubt whatsoever that The Nightingales are something worth preserving and that Lloyd’s work has significant artistic merit. Your reaction to the film will inevitably be coloured by the extent to which you agree. Plenty of people won’t, and Lee’s sweeping generalisation that “we live in a culture where mediocrity is rewarded and originality and integrity are punished” is likely to get up a few noses, whether it’s meant genuinely or is a knowingly provocative claim characteristic of his chip-on-the-shoulder cultural snob stand-up persona.

For his part, however, Lloyd refuses to take himself too seriously (at one point, reflecting on getting his fingers burned by Virgin, he catches himself and asks “Sorry, did I get too earnest?”) and regularly frustrates Lee’s attempts to do so too. “The problem with you is that you overanalyse everything,” Lloyd says, gently puncturing his interlocutor’s ruminations – a point amply illustrated by the fact that Lee read The Nightingales’ 1982 single Use Your Loaf as deeply metaphorical until Lloyd revealed it was just inspired by a stint working in a bakery.

In that spirit, then, perhaps it’s best not to forensically dissect the film. Neither is it strictly necessary to buy into Lee’s narrative that, like Monro’s sculpture, Lloyd is a towering figure due the recognition he deserves. Instead, it’s possible just to enjoy the evident camaraderie between the pair, as well as Lloyd’s anecdotes (“I’ve seen Bo Diddley in his underpants”) and the contributions of assorted famous names (Confessions… and Carry On star Robin Askwith steals the show by claiming to have “swum naked with Oliver Reed in a fishtank at the Madrid Hilton”).

Like another rockumentary, Anvil: The Story Of Anvil, which Lee admits was an unlikely source of inspiration, King Rocker is above all a frequently hilarious and occasionally touching ode to persevering against the odds, armed chiefly with what Lloyd calls “ridiculous stubbornness”.