Through Derek Walker of the Facebook Group South African War Graves, I discovered a "Forgotten Poet of the First World War" (Forgotten (male) Poets is another section of the project) - Samuel Edward Krune Mqhayi (1875 - 1945) - South African. I also learned of the existence of the South African Labour Corps during WW1.
Derek kindly supplied the following information: "The SANLC are a very neglected part of our military history. Basically volunteers who were employed to do the dirty work and who were not allowed to bear arms. Its a bit of an unsavoury part of our military history, and the loss of the Mendi was a tragedy, I dont have numbers or info on it all, but will see if I can dredge up some interesting reads about them.
They also served in WW2 although I think they were then known as NMC (Native Military Corps), and did a fantastic job wherever they went.
Many thanks indeed Derek.