Keira Knightley gets fashion tips from art galleries.

The 'Pirates of the Caribbean' actress allegedly spends her free time trawling London's National Portrait Gallery scrutinising pictures of old school Hollywood screen sirens so she can copy their best beauty and fashion looks.

A source told The Sun newspaper: ''Keira loves the classic look of old movie stars like Audrey Hepburn and Greta Garbo. The gallery is full of vintage prints of those films star and Keira spends ages checking them out to pick up fashion and style tips.

''She also spends a lot in the gift shop buying souvenir postcards pencils and art books.''

The 28-year-old brunette - who is married to Klaxons keyboard player James Righton - is clearly doing something right when it comes to nailing the retro style since fellow actress Sienna Miller recently described her as a timeless beauty.

Sienna said: ''The first thing that springs to mind [when thinking about Keira] is the 1940s. I think of her as glamorous in that kind of timeless movie-star way, but she can be grungy in this very cool 90s way.''

Keira previously revealed she loves the drama and fantasy of clothes, which have the power to transform her mood.

She said: ''I like the fantasy of fashion, creating a different person and dressing up like her. Putting on a flowery dress when it's raining brightens up the world.''