"I have definitely done a design for her, so when the phone rings, I'm ready!" British designer Sassi Holford jokes to PEOPLE. "She is simple, classy, stylish ... [and] I would show off that fabulous figure!" What better way to do that than in an utterly elegant fit-and-flare gown? Though it's deceptively minimalist, it could be the perfect palette to set off a dramatic Philip Treacy hat.