While he was still alive, I was invited to PW Botha’s home in the Wilderness on two occasions and had very interesting discussions with him.
He was adamant that his so-called “stroke” was not natural, but that he was poisoned. Apparently the dosage was not high enough to kill him, but caused symptoms not far removed from those of a stroke. However, he was examined by all the specialists at 1 Military Hospital in Pretoria, none of whom found evidence of a stroke.
As you say, the “stroke” incident was then used by FW de Klerk to depose PW Botha and embark on what finally turned out to be military surrender to a third-rate terrorist group, the ANC, which could never have taken South Africa by any other means as our army was about number 4 or 5 in the world.
I further suspect that De Klerk’s brother, Willem, had been recruited by British Intelligence even while he was still editor of the Transvaler newspaper. Shortly before De Klerk took the decision to unban the ANC and release Mandela, Willem de Klerk was called to London by British Intelligence for a stay in a hotel, after which he went back to brief FW on what the Britons thought should be done.
Robin Renwick, the British ambassador at the time in South Africa, had also engineered the demise of Rhodesia at Lancaster House in 1979, so he knew how to play the various white factions off against another to get radical blacks into power.