Avocado Prawn Cocktail

Over the last fifty years, I have seen, and served, all sorts of foodie variations on the famous Sixties Prawn Cocktail. This recipe is decidedly retro, going back to the time when a prawn cocktail was the height of sophistication. I’ve come to realize it can’t really be improved upon, except perhaps with the addition of avocado, which was an almost-unheard-of luxury then.