I noticed a structural oddity in the public lavatories at Hall Leys Park, Matlock. As you enter the gents there is a recessed mirror on the right. It's quite large, and it seems odd that it is deeply recessed. It seemed to me that the reflection was slightly less bright than normal. The attendants' store is on the other side of the wall, and as it happened the door was open. Since the attendant was busy at his van I snook in and saw that the area of wall that appeared to be exactly opposite the mirror was covered by a large sheet of plastic, held to the wall with adhesive tape.
Bill