A member of the public contacted me after finding this skin of a small snake which had been sloughed inside a lidded barbecue. They have to find somewhere rough to rub their mouth, to start the skin peeling back, then they crawl out of it, leaving it behind, often intact, and turned inside out.
The young father was concerned it might be an Adder near his garden. I could reassure him after checking with a hand lens that it wasn't an Adder. Also, unfortunately for us naturalists, it wasn't a Grass Snake either. Both these native snakes have a central keel on each small dorsal scale, which shows easily on the slough, but this snake didn't have this feature. The keel is a raised line like the keel underneath a wooden boat.
So it's most likely an escaped exotic pet. The only chance it could be a native snake is if someone has picked up a Smooth Snake on one of the few southern county heathlands they live on, and brought it home. (This would be a wildlife crime, as you need a license to handle Smooth Snakes - which don't have a keel on their dorsal scales.) Reference: ARC Reptile ID Guide (online.)