You won't believe what Rosie wore to the glamorous launch...

She's one of the world's most in-demand models who spends most of her time stateside in LA but this week Rosie Huntington-Whiteley made a return to her Brit roots to launch her first-ever fragrance and the next product in her long-standing partnership with Marks and Spencer; Rosie for Autograph. 

Of course, we're all familiar with Rosie's gorgeous range of lingerie that she designs for the high street store. Season after season, we fall head over heels for her silky camisole and short sets, wrap-round stoles and sexy bra and pant sets — so, it would be fair to say we know a RHW design when we see it. 

Our eagle-eyes were put to the ultimate test last night as the 27-year-old model turned out in serious style to the launch of her new perfume rocking an ensemble we were positive we'd seen before...

Yep, that's right; Rosie wore her UNDERWEAR to the party! 

Ok, so it wasn't a push-up bra and suspender combo but she did wear a nightie from her Rosie for Autograph range to the glittering event. And we, for one, think she totally managed to pull it off.

While it definitely takes guts to head out in your PJ's, it's not like we're talking about a fleece onesie or anything. Rosie's nightie was the epitome of chic; crafted in dove grey silk, finished with delicate white lace and offset with a daring thigh-high split, we can't blame her for wanting to show it off. 

While this exact dress is yet to hit the shelves, Rosie's SS15 collection features a garment that's strikingly similar — apart from the teeny tiny buttons at the bust, only the most seasoned fashion girl would be able to spot the difference. Check out out in full here

Finishing off her look with a feminine faux fur stole, glittering heels and an Annina Vogel cluster necklace, instantly taking her nightie from bed-wear to bar-wear. 

Imagine going to bed looking like this... One thing's for sure; getting ready in the morning would be so much easier. 

Check out the beautifully shot film for Rosie's first fragrance for Autograph below...