Part of the problem is that I don't know exactly what it is called, and it seems to have different descriptions on different sites, so searching the web is proving frustrating.
Basically, it is a bracket for attaching the end of a rail to a sloping wall or ceiling.
Ideally, I would like one in brass.
I have found a picture of just about the exact thing on this site here, but have had no luck in finding a UK retailer. Any suggestions most welcome!
theshowercurtainrodssellers.blogspot.co.uk