A study of relations at the United Nations and in the fields of economics, defence, and atomic development reveals that up to the mid-1950s, Britain and South Africa continued to be bound closely together both by common interests and by mutually advantageous bargains founded on Britain's indispensibility as a market, as a source of goods, technology, and capital, and as a military ally. By 1961, however, South Africa had left the Commonwealth. Some members had found it impossible to accommodate a country whose government was committed to repugnant racial policies. The international odium associated with those policies had, even before the 1948 election brought the National Party with its doctrine of apartheid into power, tended to isolate South Africa. In the case of Britain, this tendency was counteracted by a desire to hold the Commonwealth together, to draw economic and strategic strength from a close association with South Africa, to resist the expansion of Afrikaner nationalist influence especially where this would occur at the expense of British interests in Africa, as well as to resist United Nations interference in the rule of dependent peoples. Developments, not always readily predictable in the first ten years after the war, transformed South Africa's underlying attachment to the Commonwealth by 1960. Afrikaner nationalists had steadily secured their elec toral base and pressed forward with a dogmatic implementation of apartheid. The opening-up of the world economy, economic revival in western Europe and Japan, and the abandonment of obsessive atomic secrecy sharply diminished the monopoly power at Britain's disposal in the economic and atomic fields. The Suez debacle was a catastrophe for British prestige - military and otherwise. Above all, perhaps, Britain's accelerated withdrawal from direct colonial rule (which incidentally reduced the need for an alignment with South Africa at the United Nations) called into question a fundamental assumption, shared hitherto by most of the South African electorate, that British power would in the last resort be used to uphold white authority in Africa.