My vote goes to ...
... Joss Stone!
She looked positively lovely, and fresh as a daisy in her two-piece ensemble by Coast!
Her gorgeous straw hat was an inspired choice that set the outfit off perfectly, along with her matching shoes and clutch bag, of course!
Loved her as Anne of Cleves on The Tudors, impressed by her fashion sense, I just may have to download some of her music off iTunes!