I dont think it has a name, they called it "Mike pour me a cane", If you will permit me to name it I reckon either:
Red Lipped Herald (A water snake common to the part of Kwa Zulu Natal they lived in, Port Edward)
Pop's Magic Mooti (Pop was my grandfather and mooti is South African slang for medicine)
They were both from a long line of African colonialists stretching back to the early 1700's so I am not sure if they invented it or it was learned from elsewhere. The white rum they drank is known locally as Cane Spirit, it has quite a history behind it, a little of which you can readhere
. Its the one on the top: Mainstay. Pretty much South African pirate juice. I am sure pretty much any white rum will work just as well.