To be honest, we're not entirely convinced that it's not lingerie, or at least a nightgown. Anyway, minimal makeup and jewellery (in fact, no accessories beyond that 'it's not an engagement ring, honest' ring) plus some nude strappy heels completed the stripped-down look and showed off the fab figure which landed her the Burberry job in the first place.
Are you a fan of Rosie's party style? Let us know in the comments below.
To steal her lingerie style, take a peek at the MyDaily store:
For more of fashion from the Burberry guests, simply check out the gallery below: