Topshop is announcing its first ever Christmas campaign in suitably ground-breaking style - with a competition to guess which star it features before she is officially revealed.

GLAMOUR.com will be running a series of beautifully shot clues - this video, and jigsaw-puzzle piece image, being the first - to help savvy style fans work out the mystery blond's identity.

Think you recognise her? Tell Topshop your hunch at topshop.com/whosthatgirl - ahead of The Big Reveal on 4 December - for your chance to win a ??500 shopping spree.