Hello Nick,
The Umtali Burghers were part of the volunteers recruited for the 1896 Matabele war, there is a roll for them in WO100/77 at Kew, they had a very well known commanding officer for part of their short life, Captain TB Hulley, a larger than life character in Umtali and a friend of Cecil Rhodes, I am sure that I do have a couple of photographs of some of the Umtali Volunteers, but, I can't remember which unit they depict, you had the Burghers, Volunteers and Artillery etc, moreover I'd have to look for them.
From a medal point of view, you do see the odd one turning up from time to time, however, in keeping with BSA Company medals in general, they are quite rare things, there was a bullion dealer in Bulawayo buying them for scrap in the 1970's, but then, those days were very hard for many people in Rhodesia, everything was in short supply, even basic food stuffs, milk in particular could be a problem in Umtali during the war!
So why the interest in Umtali Burghers?
Kind regards Frank