I am writing this as I read it. Nyasaland was a British protectorate from the late 19th century, it is now Malawi. As the book expresses it the British empire sat quite lightly on the place. There were however multiple attempts to join it with Northern Rhodesia, Zambia, and Southern Rhodesia as the Central African Territories. This was strongly resisted in he first 2 as they were only lightly settled and the Native population know how life was in Southern Rhodesia and weren't being subjected to the same rule.
There are long passages explaining how the apartheid system wad legislated for how it was supposed to work and how it actually worked. The book points out that pass laws in SA had filled the jails while in Rhodesia they hadn't because they weren't actually enforced. ( )