I'd heard it before - I was going to copy/paste it and put it in the Monday joke thread (guaranteed 3 or 4 easy likes), but that would have been dirty play!
Used to get fantastic Roll Mops from the fresh fish stall in Catford (with chillies inside). Can't get decent ones nowadays. Tried a few places near me but they had some sweet muck in. Given up.
Also used to get Arbroath Smokies there too. Not seen any for years now.