British director Molly Manning Walker won the coveted Un Certain Regard newcomer prize at Cannes on Friday for her much-praised feature debut How to Have Sex.

"This film was the most magical moment of my life," the 29-year-old Londoner said after receiving the prize, which she dedicated to "all those who have been sexually assaulted".

The film follows three best friends getting drunk in Crete, with one of the girls, Tara, on a mission to lose her virginity -- but things soon go wrong. 

All the stereotypes of Brits abroad feature in the film but Manning Walker also sought to break them by digging deeper into the thorny issues of rape and consent.

It caused a storm at this year's festival and drew rave reviews.

Variety found it "chillingly dark", The Guardian admired its "complex chemistry" and The Hollywood Reporter dubbed it a "hidden gem".

Drawing from her own experience, Manning Walker speaking to AFP earlier during the festival, said she was inspired by "the best times of my life", but also the sexual assault she suffered at 16 -- and wanted to show it all without judgement.

Shot in a fly-on-the-wall style, she resisted showing graphic assault scenes.

"I think we as women know that experience way too much -- we don't need to be re-traumatised," she said.

Instead, she focused on her characters' emotional experiences.

"Everything was from her eyeline and everything was on her face and reading her emotion," she said.

Manning Walker is one of an emerging crop of exciting British woman directors alongside the likes of Charlotte Wells whose Aftersun was last year's unexpected breakout at Cannes, earning an Oscar nomination for star Paul Mescal.

Before directing she was a cinematographer for nearly a decade and shot films for other young British talents including Charlotte Regan's Scrapper that won the Grand Jury Prize at the Sundance film festival this year.

She has also made music videos and adverts, as well as two short films including Good Thanks, You? that screened at Cannes in 2020.