Cara Delevingne and Sienna Miller, what on earth are you wearing?

Cara Delevingne is one of the world’s most sought-after supermodels – and Sienna Miller is a style icon in her own right.

But the normally chic pair made a fashion faux pas in their outfits for a night out in London yesterday.

Laid-back Cara – who turned 21 this week – rocked a bizarre ensemble of a pyjama-style shirt with a masculine-looking grey suit.

The face of Burberry Body fragrance styled the bonkers look with a pair of black army boots and a rainbow-coloured cap back to front.

The Brit model ditched the make-up for the night out at London’s Groucho Club, opting to go bare-faced for her night on the tiles.

Also joining Cara in the capital was the new face of Burberry’s Autumn Winter 2013 campaign, Sienna Miller.

The New-York based actress, 31, rocked head-to-toe floral print as she walked arm in arm with fashion designer Matthew Williamson.

The mum-of-one rocked a ‘70s vibe, wearing a printed bodysuit tucked into a pair of ditsy-print flared trousers.

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Tom Sturridge’s fiancé styled the look with a pair of black raffia wedges and a croc-skin clutch for her night on the tiles.

Cara’s older sister Poppy Delevingne, 26, could teach them a thing or two about laidback luxe as she stepped out in this effortlessly stylish ensemble.

The Vera Moda model wrapped up warm in a pair of distressed denim jeans, a loose grey tank and sleeveless fur gilet.

Poppy styled her outfit with a pair of mint green cowboy boots and a black Birkin tote, which she wore to meet Sienna, Matthew and little sister Cara at the London restaurant.

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What do you think of Sienna and Cara’s style? Tell us over on Twitter now.