Andrew Durham’s long-awaited adaptation of Alysia Abbott’s memoir begins, like so many stories, with an orphan.

As Fairyland opens, Alysia (initially played by Nessa Dougherty) is a child in the back of a groovy Volkswagen Beetle, heading west after the sudden, barely grasped death of her mother. Steve, her mild-mannered dad, is San Francisco bound with his daughter, much to concerned chagrin of her grandmother (a hugely welcome Geena Davis).

Their new, freefalling, communal existence, shaped by lovers, writers, performers and late-night parties, isn’t always the ideal environment for a little girl. Afforded independence that would make contemporary helicopter parents call for a stretcher, the youngster is almost accosted by a strange man in a car on an unaccompanied commute from school. “You’re neglecting me,” she pouts (not entirely unreasonably) at her dad.

And so this fond, wise, lived-in film chronicles a spectrum of parentification – with the parties switching roles – over turbulent decades. Its emotional force is found in the two-step between parent and child as the sweep of LGBTQ+ history catches up.

As young Alysia, Nessa Dougherty watches the adult world with solemn concentration, absorbing rooms full of smoking revellers and strangers asleep on couches, and accidentally seeing testicles.