Lessing documents the nature of the political and cultural milieu of Southern Rhodesia in the mid-fifties. In many ways this is an excellent historical investigation in journalistic prose.
My concern is with the book's underlying assumption that that those who left Britain to occupy the colony either became less moral, or were already less moral, than those who stayed behind. Lessing tends to represent those who remained back in Britain as denizens of proper and correct behavior. Life in Africa is thus seen to exert a corrupting influence on otherwise wholesome and correctly mannered British people:
"Why was it that when white people came out from Britain, first they were indignant about the colour bar and the treatment of the Africans, and then they very fast became as rude and cruel as the old Rhodesians?" (p162)
I feel the book has the quality of being a bit dated for its moralizing perspective.
"Africa belongs to the Africans" and Europe belongs to the Europeans is the underlying premise of the book -- and although it is unspoken, it comes across in many different ways, such as in the formulation quoted above.
What needs to be examined, in order to give a sense of context to the book, is whether attitudes remain automatically "civilized" so long as they do not go abroad.
Also, are black Africans not similarly subject to "corruption" by virtue of living in Africa -- or is this corrupting effect of the continent only effective on the whites who have gone there?
Lessing's book attempt to teach a moral lesson about colonialism, but leaves these fundamental philosophical questions unanswered.