The “prom dress” is now such a modern classic that you can even pick one up in the supermarket! F+F generally have a good range of those fitted bodice, full knee length skirt, type dresses that can be accessorised for everything from a classic modern look, to full on 50s.
This one has a nice bold floral print on a black background. I like floral prints with black as they’re easier to team with stockings and a cardigan for winter. It’s also in the sale, in all sizes, though stock is limited in the larger sizes.