Swivel-eyed, finger-wagging and with an ever-present scowl beneath his insurance-salesman's trilby, Mr Botha was perhaps the most enduring icon of apartheid. But here he was, calling to ask President Mandela for a "favour" - he was seeking the early release of a former cabinet colleague, Pietie du Plessis, jailed for seven years for fraud. A BBC film-crew document the moment, which now stands as a reminder of how things in South Africa have changed in such a short time.
Mr Botha, the "Great Crocodile" himself, a politician whose main philosophy on leadership was that a "man must not be a jellyfish", was petitioning someone whom he had made sure remained locked away during his 11 years in power.
Mr Mandela, for his part, was courteous and patient, showing no signs of animosity towards his old tormentor. Perhaps he sees the elderly Mr Botha's final days, spent as a recluse in simmering resentment, as punishment enough. Overtaken by the very modest reforms that he had put in place, such as allowing Asians and so-called Coloureds into parliament, Mr Botha was forced from office in 1989. His resignation, which came just after he suffered a stroke, was bitter and vengeful.
A year after being ousted, he quit the National Party (NP) in protest at the start of talks with Mr Mandela's African National Congress (ANC). It was a desperate move for a man who had been an NP activist all his life. Mr Botha first entered parliament in 1948. He served six years as prime minister from 1978 and then became state president for the following five.
Today, aged 79, he spurns publicity. Several newspapers and magazines have asked for interviews, but have been repeatedly turned down. He lives in near-isolation in the Cape Province with his wife Elise, who last month emerged from the Wilderness to make an appearance with President Mandela and to attend a special reconciliation lunch for wives and widows on both sides of the struggle over apartheid.
Despite his bitterness with his former colleagues, Mr Botha is said to be on "friendly" terms with Mr Mandela. Nevertheless his disapproval of the direction taken by South Africa is clear, if quiet. Before his vow of silence, he said: "Remember, it was I who started political reform in this country." But he added that he saw a distinction between reform and the "gradual abdication" of his immediate successor, FW de Klerk.
For a long time Mr Botha was said to have nothing but contempt for Mr De Klerk, whom he blamed for ousting him and throwing away white minority rule. However, following a visit to the Wilderness by Mr De Klerk last year, the two men were said to have settled most of their differences.
Although he has been out of power now for almost six years, he is still a main target of South African satirists, such as Pieter-Dirk Uys. In his latest hit one-man show, "You ANC nothing yet", Uys has used Mr Botha's life in the Wilderness to mock the new ANC government. He portrays Mr Botha in a cook's apron tending a barbecue in his back yard, spouting poison against Mr De Klerk and the new government. By all accounts, it is an accurate depiction of Botha: a sour old man, desperately clinging to the past.