No movie with wall-to-wall Diana Ross music can be all bad. But this one-off celebration in honour of Ross’s 75th birthday seems weirdly thrown together, at times like a video tribute created by her children and grandchildren to be shown at a family party. It’s not a full life story but a revisiting of one of her finest hours: the 1983 free open-air concert in New York’s Central Park, which was engulfed by a terrifying thunderstorm.

Like the showbusiness legend she is, Ross turned this into an anti-Fyre festival triumph. She kept singing in the drenching rain, speaking soothingly between numbers, starkly lit by a spotlight in the darkness, and kept the audience miraculously calm. If she had simply abandoned the stage, there could have been dangerous panic as everyone galloped blindly for the exits. Fortunately, an extra performance the next day enjoyed sunny weather and we can see what live shows looked like in that innocent age: Diana in a few hi-vis changes of costume, a single big screen and a simple wooden stage-platform that bounces dangerously as Diana dances on it.

The final 90 minutes of this film is simply the footage as it was transmitted live on TV at the time, with none of the editorial perspective you would expect. Beforehand come the gushing tributes from her family and a piece to camera from Barack and Michelle Obama. There is an especially strange bit where her daughter appears to be addressing Diana, off camera, praising her for the legendary courage in dealing with the storm and telling her: “You are the most beautiful thing in the world!” But we don’t cut to Diana. Was she even there in the room? Or did she nix the reaction shots? It’s strange. And then … well, it’s just the show itself. It doesn’t really give us the “life, love and legacy” as promised.