Nighthawks is worth watching for its opening scene alone, a fabulous eight-minute creep through a late-seventies London gay bar that’ll have you reaching for your poppers bottle. The film is fairly average, quite bland in structure and style, but it has aged marvellously, maturing into a fabulous gay film classic, a veritable museum piece, just the thing for colour-starved, politicised twenty-first century gay audiences. In the cast, horse-faced Maureen Dolan is the highlight, her boggle eyes and quizzical nature making her a dead ringer for Shelley Duvall in The Shining.

Full of hairy arms and dirty undies, the whole thing is so pre-clone, pre-post-AIDS it’s just wonderful. There isn’t a Muscle Mary in sight and the gay guys actually talk to each other like normal people, asking about work details, family history - normal, stilted one-night stand conversations conducted on jewel-coloured bedspreads inside tiny, grotty bedsits.

Jim (Ken Robertson) flip-flops between his job as a high-school geography teacher and his nights at the bars, endlessly and aimlessly cruising for sex and connection. The film flip-flops with him, alternating – literally – between classroom and disco from film start to film finish. Don’t expect any surprises or sudden departures from this back and forth structure. The film has only four settings: the classroom, the disco, Jim’s flat, and a bar where Jim hangs with his workmates. A sub-plot involving Jim’s curious female colleague (Dolan) goes a short distance, as they chat about his homosexuality, and not much else. The “startling climax” is little more than a Q&A between Jim and his ignorant, yet curious, pupils about being gay and how two guys “do it”.

Jim can’t reconcile his work life with his night life, and this seems to be the grist of the plot. In hindsight though it seems that Jim is presciently identifying that high-octane gay disco backroom promiscuity will never find a place in the mundane nine to five. He needs to split his job with his private life, as there’s just no way the two can come together. But this is the appeal – the groovy seventies atmosphere of the whole thing, full of sideburns and innocence and totally free of socio-political grandstanding, pleas for tolerance and (praise Jesus) the dreaded post-AIDS brigade of ACT-UP, Queer Nation and so on.

As with any gay-exploratory movie made in the years just before AIDS, there’s a haunting sense of the tragic hanging over Nighthawks. There’s a real curiosity in the film, a sense of enterprise around looking at new ways of living, new ways of being adult and new ways of being sexual. Nighthawks, like Making Love, seems to have endeavoured to explore the complexities and barriers between gay and straight, as well as spotlight the potential for common ground. Alas, things were soon to change.