Hello Mike,
I am sorry if I appear to you to be rather circumspect, it does seem to be a family thing and is sometimes mistaken for reticence.
With BSA Co medals, many people use the published rolls of Colin Owen and Don Forsyth, I prefer not to, really because of the errors in transcription, but, one of the problems is that WO100/77 is, well, a bit of a mess really, you have main rolls, supplementary rolls and distribution rolls etc, moreover, I don't have to, although it is now partially digitised, I had my own copy made some twenty years ago now, in several bound volumes and I always work with these.
Anyway, I'm happy with your man and I believe him to be Arthur Richardson, there was an issue with the clasp, but, really the faint annotation on the 1897 Mashonaland medal roll does suggest he is the same man who is shown as Trooper A Richardson Salisbury Field Force.
Richardson may have joined the Salisbury FF after June 1896, however, he might well have served before in the Rhodesia Horse Volunteers or the Salisbury Horse.
In late June or very early July, both they and a body of local Burgers merged together and became the Salisbury Field Force, from memory, they were disbanded in mid October, the following year.
I suggest it was after this point he joined the British South Africa Police, perhaps even as a junior NCO, he is however shown as 291 Corporal and as I have already said, the address given as far as the entitlement to the Mashonaland 1897 clasp was that for Cheam in Surrey.
If this group was mine, I would now consult WO126/30 at Kew, if his attestation into the Colonial Scouts has survived it might well make for very interesting reading indeed and you might see an immediate and obvious link.
Moreover, because of his service in the Mtshwti Rifle Association, followed by his time in the Colonial Scouts and wartime service in the Carbineers, I think you are looking at a man who went on from this to be a local Natal gentleman, so I think I would also consult Jenny Duckworth in Pietermaritzburg as soon as you can.
Regarding his time in Natal, you might be forgiven for thinking it must be really rare, but, if so, it is certainly far from unique.
As you may recall, I was myself, last year, the focus of a number of jokes because I was the only member of this forum, indeed, I dare say too, the only person in the civilised world, who did not have a Natal Carbineer in his collection!
Anyway, I have since been able to just go out here and buy several examples without any problems at all, moreover, I make mention of this only because the very first one was a man, who, just like your man, was a member of a Rifle Association, then a member of the Colonial Scouts, Number 2 Troop of "D" Squadron, which I think from memory was the Mooi River Troop and just like Ricardson, he too, had served until disbandment and then joined the Natal Carbineers.
So there you are, Richardson was not alone in doing this sort of thing.
You could and should take this much further,
Kind regards Frank
Owens published roll, note the vertical columns and the entries for Richardson, appears to be differant men and two differant medals!
The originals for A Richardson Salisbury FF