A fine collection of photos from former Nyasaland, Northern and Southern Rhodesia are to be found at this web-site link:
There are other African countries represented too, and gen on many interesting cars. Some examples are here:
There is not much known of the numeric-only Rhodesian plates which the first vehicles used. South Africa used identical plates at the time – note this Transvaal example below:
And, from Western Australia:
It seems that many (Empire) jurisdictions didn’t expect the expansion of motorcar populations, and thought a simple numeric format would suffice!
Evidence that Britain also influenced early China plates is shown here:
Enjoy the Classic cars in Rhodesia website! http://www.classiccarsinrhodesia.co.za/Makes/SWA.html