New queen of period dramas Keira Knightley is in her element here, donning skyscraper hairpieces and unfathomably complex robes to play a rock ‘n’ roll noblewoman in a time when her sort were expected to shut up and produce babies. Ralph Fiennes is equally well cast as her pathetic older husband – loveless, merciless and desperate for a male heir – and for the most part things play out pretty much as you’d expect, with über-glamorous party scenes, British Tourist Board-friendly stately home shots and costumes that will make needlework aficionados swoon.

But the film is underpinned by frustration and sadness, so amidst the high society set pieces there are moments of impressive grit and realism. Georgiana is played as a loving mother, torn irreconcilably between the children she has and the life she desires, and in the moments where these feelings are tested to the limit, Knightley’s performance is powerful, verging on harrowing at times. Meanwhile, Fiennes puts in a superbly taught display. He hardly says anything for much of the film, the Duke’s pitiful lack of compassion is portrayed through darkly comic grunts and glares rather than elaborate speech.

It’s a relief that the film doesn’t overplay the Princess Diana parallels – it wouldn’t have taken much for this to have become as crass as some of its early marketing (“There were three in her marriage…” etc). As it is, the echo of Diana’s tragic tale just shows that while the dresses may be a little more practical these days, behind the scenes the British aristocracy is still a shadowy place for independent females, while The Duchess stands alone as a quality costume drama with dirt under its immaculately painted fingernails.