hmm, I simply thought: there's only one large river IN Kent, the Medway. So what decent sized towns are there: Maidstone (discounted), Rochester, Chatham, Gillingham and Sheerness. Well the Medway Towns are the larger group, middle-for-diddle it means Chatham somewhere! If Beachbum is keeping his head down and dodging this one, I have a look through my catalogue to try and puzzle you all tomorrow.
OK, try this one: