Even though it's attributable more to the novel it's based on, this movie scores points straight out of the gate for having such an original premise – I don't think any of us have ever seen a young adult feminist adventure set in feudal era England.

Catherine (Bella Ramsey, at pre-The Last of Us-level stardom) is called Birdy as a nickname, mostly by her devoted lady in waiting Morwenna (Lesley Sharp), because she keeps birds as pets.

Feisty and determined to make something of her life beyond just marrying and having babies to some nobleman, the feisty 14 year old is growing up in the decidedly unenlightened England of the thirteenth century,

The set-up of the film is Birdy's own narration about her home and family, from her austere and slightly bumbling father, a local Lord, to a mother (Billie Piper) that's loving and optimistic despite having lost so many children in childbirth.

Birdy has three older brothers, a knight, a monk and a kid like her. She has a best male friend in local boy Perkin and a close sisterly friendship with noblewoman Aelis, a girl her age from a few villages away.

What she doesn't fully understand is that the family finances are dwindling, and unless an alliance can be made with some rich Lord or noble, Birdy's family will lose everything.

Despite her headstrong refusal to do so, Birdy's father insists she has to entertain potential suitors in order to find a wealthy husband so she can marry as soon as she comes of age, the only way they'll stave off poverty.

Horrified at the impending loss of her agency and freedom, Birdy sets about doing everything she can to repel and rebuff everyone who comes her way hoping to get his hands on the family's coffers.

As those around her try to tamp down her most outspoken tendencies, Birdy holds firm, trying to live her life her way while she still can.

She'll deal with a case of teenage infatuation with a handsome Uncle who returns from the crusades and gives Birdy her first real heartbreak, her mother's continuing efforts to give the family a surviving heir and even the shock of her first period, all of it fodder for for Birdy to reconcile her place in the world along with her own unshakable desire for freedom.

Based on a 1994 children's book, it's easy to see why writer/director Lena Dunham loved it and has apparently wanted to make it for ages.

Despite being set almost a millennia ago, it's a feminist treatise that's not only full of fun and energy, it's as relevant now as it was unthinkable back then, all about how girls are people too and have every right to choose how they want to live (and to humanity's shame, the patriarchy and marriage-as-market is as alive now as it was in the Middle Ages).

Like Greta Gerwig managed with her version of Little Women , there's an extra dimension of production design, costuming and location work we haven't seen from Dunham before, establishing her as a director who can convincingly create a world rather than just point cameras at the world most of us live in.

What's even more clever about the whole film however is that her script (together with Ramsey's spirited verve in the lead role) is far less concerned with historical accuracy than it is with saying what the movie has to say.

Plenty of elements from Birdy's attitudes to the terms people use in conversations are stylised – almost modern – and instead of jarring they feel as natural as any of the visual motifs about pre-industrial life on screen.