>>>Arguably the poster child for "effective" sanctions was South Africa...
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>And perhaps those against Rhodesia before that. But Margaret Thatcher called the SA sanctions "the way of poverty, starvation and destroying the hopes of the very people- all of them- whom you wish to help." John Major said disinvestment would "feed white consciences outside South Africa, not black bellies within it" though he backtracked later.
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>My question would be whether it was the sanctions that brought an end to Apartheid or whether it was an archaic imperial ideology whose time had come.

I suspect since the Mau Mau rebellion in Kenya (if not earlier), the writing was on the wall for European colonialism in Africa. Perhaps due to its relative prosperity, SA hung on longer than most and it's to that nation's credit that a relatively smooth transition of power was negotiated.