As I said at the beginning of this thread, the other obvious consideration must be The Yeomanry Cavalry whose Officers Lists are difficult to obtain...
The inspector and date markings look legit; the year and inspector markings are partially worn, but the inspector was likely Archiblad H. Ceiley. He...
Additional Hardcastle info: his mother was Elizabeth Augusta Smith of London, and the Smiths of London had the lion emblem. If he's the one, perhaps...