I'm not sure that your method, Tony, is foolproof.
My British great-uncle, Roland Levy, served in a battery of the South African Heavy Artillery, which became the 71st Siege Battery RGA. I have his full service record, but I couldn't find a medal card for him.
Elinga - it must be 15 years since I acquired Roland's records. I'll check my notes to establish how I did it. I seem to recall that I had to contact the military archive in SA. I should also mention that I have photos of him in uniform and my late father knew that he had been an artillery officer.
Justin