She is usually listed as a Size 8½ US. The shoes pictured are Jimmy Choo, Size 38, which is Italian sizing. Size 38 IT = 39 EU = 8 US = 5 UK. But Choos can run large. Daily Mail UK has *proof* from a display of her wedding garb at Buckingham Palace: "The duchess's hand-stitched shoes were designed by Sarah Burton of Alexander McQueen and are size five-and-a-half [UK]" So 5½ UK = 8½ US. There you go, proof positive.
Ah, my comment was deleted. I guess harsh language is a far graver offense than having pictures of young children on a fetish website. Totally makes sense. But seriously, something needs to be done about this.