How do you know if you’re knocking on a bit in this fine county of ours? When you remember going down the water chutes at Fantaseas in Dartford? Or perhaps riding the Mary Rose at Margate’s Dreamland? The reality is that when you start remembering the things you have done and experienced over a lifetime it can make you sound very ancient indeed to today’s young whippersnappers. Recalling how every town’s high street used to be packed both with shops and shoppers – in a pre-Bluewater, pre-out-of-town developments era – will leave many youngsters looking bemused. So read on and see how many of t…