I love how there are already a ton of northerners calling out southerners for their lack of geography knowledge when it comes to the rest of the country LOL. Good job OP for making the point, I'll be honest, I hadn't heard of Leeds castle before but given my own knowledge of Leeds itself it wouldn't really surprise me there wouldn't be much in the way of a large countryside and castles there because it's something of a sprawling metropolis at least by northern standards.
RE: Leeds Castle is not in Leeds