Kate Middleton's New Look

Hours after Kate Middleton, Prince William and Prince Harry turned up in Greenwich, London to cheer on cousin Zara Phillips at the cross-country equestrian event, the Duchess of Cambridge took a solo turn out on the town in a sleek and stylish new way.

Ditching her more casual, preppy garb, Middleton, 30, looked elegant in a dove grey wool crepe Roksanda Ilincic frock and pinned her signature blown-out locks back in a chic chignon.

It's not the first time Middleton has stepped out in the Lilac frock - Kate also rocked it for her arrival in Los Angeles for her Summer 2011 Royal Tour visit to the U.S.

At the event, Middleton mingled with fellow partygoers and "especially enjoyed chatting with Stella McCartney," a source told Us Weekly. "They spoke about the Olympics and the opening ceremony . . . and fashion, of course!"