The mystery object of 25th November identified. I was sure the pattern of the ridges on it reminded me of something; I realised yesterday it was the grooves cut in a millstone. After quite some online searching: it is part of the iron cutter plate of a Victorian / early C20 farmer’s corn grinding mill (possibly horse or steam driven). Here’s the photo of the original object, with below it a website picture from an Indian engineering company still manufacturing spares for the same sort of mill – probably these days driven by a stationary diesel engine.
