Kristen Stewart’s fragile portrait of Diana, Princess of Wales, is the crowning achievement of Pablo Larraín’s chilling and restrained biopic.

If this is a ‘fable from a true tragedy’, the way Larrain harnesses that tragedy ends up being just another way to define Diana as a victim.

In a breathless, headlong way, Stewart does a credible job, but she’s perched on the edge of hysteria throughout and the upbeat ending fails to alter the impression that she and Larraín have delivered a one-dimensional portrait of a victim.

While I enjoy nothing more than images of sad girls in gowns, Larraín’s film risks overstating Diana as an avatar for suffering. Steven Knight’s sometimes corny script, which dwells on her gloom and presages her doom, doesn’t help.