A “spellbinding” period drama starring Keira Knightley is streaming for free in the UK. The Duchess (2008) is a historical drama about the tumultuous life of Georgiana, Duchess of Devonshire (played by Knightley), an 18th-century aristocrat.

She ascends to the British elite through her marriage to William Cavendish, the Duke of Devonshire (Ralph Fiennes), but the relationship is loveless and behind her privilege and luxury lies a complex tale of forbidden romance and betrayal. The film is directed by Saul Dibb, who co-wrote the screenplay, and is based on Amanda Foreman’s 1998 book Georgiana, Duchess of Devonshire, an acclaimed biography of the troubled royal.

Fans flocked to IMDb to praise the film, one of whom said it’s among their “favourite films of all time” adding that Knightley is “superb in this role”.

“Although it may not be wholly accurate, this film clearly shows how badly women (even those of high birth) were treated by men and society,” they added.

“The costumes and settings are delicious. Love love love!”

Another called the movie “spellbinding”, writing that after “reading copious amounts of mediocre reviews for ‘The Duchess’, I wasn’t expecting much from this film.

“However, from the first scene I was utterly absorbed. The film isn’t ‘just another period drama’, it is an absolutely beautiful and heart-rendering tale” of the tribulations women faced at the time.

However, not everyone was bowled over by it. One fan said the film is not Knightley’s best performance “(that was probably “Atonement” with “Pride And Prejudice another success) but it is perfectly competent, even if – unlike her wig – it doesn’t catch fire”.

Another said: “The story is a little uneventful, with some parts feeling as though they were skimmed over(the political life) or only briefly explored, and the pacing can be pedestrian.

However, they added that “it is a visual feast really, as the costumes, sets, scenery, cinematography, interiors and even the carriages are spectacular, while the music gives a lovely touch to the proceedings too”.

Another said they went in with low expectations but were impressed by Knightley’s performance. “Yes, it’s from the director of Bullet Boy – but I’d only ever seen Saul Dibb’s Line Of Beauty so I was expecting a pretty standard period piece with Keira Knightely – who I have never rated much as a credible acting talent,” they wrote.

“Boy does she impress here – she is fantastic. The Duchess of Devonshire is the perfect character for her to play, and it’s obvious Keira immersed herself in the role, and completely understood every single motivation of her character. I recommend everyone to go and see this film!”

The film has 12A certificate and contains sexual violence, and moderate sex, so viewer discretion is advised.

The Duchess is streaming now on BBC iPlayer.