Jason, I think you're an absolute star!
The river Dee runs through Chester, 7 mile away, The Groves has a band stand with lots of flat hard ground, park benches, railings, large steps down to the river, flights of steps up to the city walls, bridges over the river, from what you said it fits the bill perfectly.
If you want to have a look, put “The Groves, Chester” into Google, the area to the right up to the bridge.
Parking’s not brilliant but you can’t have everything!
Now all I need is the rain to stop and a day off work to go check it out.
unless anyone has been bocking there???