It's widely thought that all of our domesticated Beetroot varieties were originally cultivated from Sea beet. There's a familiar, beetroot note to the raw leaves, which narrow to a spear headed point in much the same way as its garden-dwelling cousin. As the name would suggest, it almost exclusively favours the coast; I've found it in abundance from the beaches of Devon to the furthest reaches of Cornwall.
Try cutting a large handful of leaves into thin ribbons, sauteing them gently with a finely chopped onion in olive oil, before stirring in cooked orzo pasta and finely chopped Ramson leaves. Serve with grated Pecorino and a good grind of black pepper.