Kate Bosworth goes for red at the premiere of her film, Black Rock, at the Sundance Film Festival.

Nice dress, but it's the clutch which is really tickling my fancy. If you're in any doubt as to what to carry to your next formal do, a box clutch is top of the list. Kate's is a sleek envelope style in shiny silver, but they come in all shapes. Just make sure it fits neatly in the palm of your hand and you don't have junk spilling out the top (they totally enforce a streamlining of makeup to take for touch-ups).

I went to the world's most beautiful wedding on the weekend (I don't joke, it was like something out of The Great Gatsby) and a box clutch was the bag du jour. They go with everything from palazzo pants to bohemian maxi dresses and, as Kate demonstrates, sexy red cocktail frocks.