Stripped of its padding and reduced to its principal theme, Butterfly is about the feeling some people have that they were born in the wrong body, a condition known as gender dysphoria. Specifically, it’s about the way it manifests itself in pre-pubescent children and the stresses it puts on them as a result. Dressed up as a three-part drama it became, in the hands of writer Tony Marchant, a sensitive discussion about that and about all the other things that intersect with it: parenthood, childhood, prejudice, biology, psychology, family, society and the qualities required to offer unconditional love.

At the centre of the discussion is 11-year-old Max Duffy (newcomer Callum Booth-Ford), who identifies as a girl but is physically male. As episode one opened we saw him negotiating the very different relationships he had with his mother, Vicky (Anna Friel);his father, Stephen (Emmett J Scanlan), now separated from Vicky and living elsewhere as episode one opened; his teenage sister, Lily (Millie Gibson); and, of course, with the wider world. For Max it’s a place of confusion – does he use the girls’ toilets or the boys? – and of peril, where bullies and name-callers wait in school corridors and playgrounds.

Stephen’s inability to cope with Max’s desire to be a girl is what caused him to walk out on the family in the first place. He still thinks his son can be “fixed”. To appease him, Max goes through the motions by dutifully kicking the football in the park. Vicky is just trying to cope by establishing rules: Max can dress as a girl and wear lipstick but only in his room. Lily’s the one who finally gets it and fronts up to both the bullies and the parents on Max’s behalf.

The script’s based on meticulous research and first-hand testimony and Marchant has pulled out some stories which clearly have wide resonance, such as when Max attempts suicide. But no two stories, no two people and no two families are exactly the same. It’s a point made by a trans vlogger in a video Max watches on a laptop, but it applies equally well to the characters Marchant creates and the situations he puts them in. So if some of them seem to strike a wrong note from time to time, you have to just accept that every family is different.

The other participant in the discussion, of course, is the viewer. Some will have personal experience of gender dysphoria or its consequences, most will have an opinion about it and doubtless some of those opinions will veer towards what you might call the Daily Mail end of the spectrum. Nothing seems to divide opinion these days like the prefix “trans”. But in Butterfly, Marchant has made a decent stab at showing how one divided family tries to re-unite around it.