Had this email from Malcolm Monie of the Whitchurch Water Vole Group:
Geof Brown of Property Sevices at NSDC has confirmed, after consulting their legal department, that the grass and bank is NSDC's.
So no one's supposed to interfere with it without going through North Shropshire District Council and the Environment Agency. Glad that's clarified.
The place is looking awful now because every scrap of rubbish shows up, and the trolley's still there merrily accumulating debris. Sometimes it's hard to keep positive, but I really hate pessimism because it saps your energy. I'll just have to get out there with my litter-picker.