Be still my beating heart. The Duchess of Cambridge made an appearance at the Epsom Derby today, and to say she looked good would be the understatement of the year. She looked absolutely dazzling! The jury is still out on the designer of her immaculate chic outfit, and whether it was a designer number or a High Street find (the jacket may be from Joseph), but what I do know is that the off-white dress and jacket looked absolutely amazing against her Seychelles suntan. Teamed with classic nude accessories, including a tiny clutch bag, and a gloriously neat  1930s style fascinator, this was a super-stylish choice and one of my…