Historians here are finding gems in the latest batch of government papers released, in this case Mrs Thatcher's foray into matters Southern Africa, entitled'Revealed: Margaret Thatcher’s ‘Marshall Plan for southern Africa':https://theconversation.com/revealed-margaret-thatchers-marshall-plan-for-southern-africa-70541?

I'd forgotten her visit to Namibia (then in 1989 South-West Africa), just as SWAPO sent thousand of fighters across the border and the South Africans came close to ending the peace settlement.

Right place at the right time was actually in London earlier:
Although Botha was in no position to make any final commitment on behalf of his government the message Thatcher left him with was clear: end apartheid, release Mandela or South Africa will face increasing sanctions. What is really revealing is that she dangled the prospect of such substantial aid in return.