Thank you, ceesnan. I do feel better now. There's nothing like having a good old grump on gransnet to put things in order again 
River, i think you're right in general terms. However, see this: "After the Labour Party sweep to power though, commitment to the anti-apartheid cause dissipated. In short order, Labour Party leader Harold Wilson told the press that his Labour Party was "not in favour of trade sanctions partly because, even if fully effective, they would harm the people we are most concerned about - the Africans and those white South Africans who are having to maintain some standard of decency there."
I remember that reservation and it troubled me at the time. I was very pleased when black South Africans started getting the message across that trade sanctions (the boycott of SA goods, etc) did help their cause.