Despite its widespread rating as one of his masterpieces, Frederick Ashton’s Cinderella is chock full of knots, gaps and stumbling blocks – all of which the Royal Ballet’s new production throws into relief. Ashton isn’t altogether to blame: Prokofiev’s graphic score dictates an excessive amount of time given over to knockabout for the Ugly Sisters (mostly a matter of them bumping into each other) and a tiresome court jester.