‘It used to be paradise. Now it’s a straight club.” The dismay is obvious when a bunch of former regulars at Studio One, the legendary West Hollywood gay club, take a tour of the venue in 2019. From 1974 until 1993, 9pm to 2am, seven nights a week, men packed the dancefloor of Studio One. “It was the happiest place on Earth,” remembers one. Looking at the photographs you can almost smell the sweat. One ex employee says that so many guys were taking poppers you could get a head-rush high simply by breathing in on the dance floor.

The story of Studio One is told in this affectionate, nostalgic documentary. Film-maker Marc Saltarelli interviews men who were there and follows a campaign in 2019 to save the Studio One building – a former factory – from demolition. When it opened in 1974, homophobia was rife outside. Studio One was a place where you could go to feel safe and loved. Though really, that only applied to white men; the racist door policy at Studio One was so well known the LA Times ran a front-page story about it.

The club’s owners went on to open The Backlot, an adjacent live music and performance venue that attracted Hollywood A-listers. But the happy ending of gay men finding acceptance on the dancefloor was ripped away in the early 80s. Like any documentary about gay culture of that era, you are girding yourself for the arrival of Aids. The club’s longterm barman Michael Koth shares a staff Christmas photo from 1980, or maybe 1981. “There are 105 people in that picture, and only two of us are left alive.”

At the beginning of the film you might be a bit cynical about the mission to save the place. It’s not as if it’s possible to re-bottle the magic of a club in its heyday, so why bother? But listening to the survivors will completely change your mind about preserving its status as a cultural landmark, perhaps even a memorial to those who were lost so young. “This was the place where they were happiest.”

• Studio One Forever is in UK cinemas from 18 October.