Yes, in 1947, when she was Princess Elizabeth.
And was that visit a success?
It was thought to be a triumph. On the night of her 21st birthday, she made a speech in which she addressed the people of the British Commonwealth and Empire "wherever they live and whatever race they come from and whatever language they speak".
And what did she say to them?
She told them "If we all go forward together...we shall be able to make this Commonwealth an even grander thing - more free, more prosperous, more happy and a more powerful influence for good in the world than it has been in the greatest days of our forefathers."
And were her South African hosts inspired by her message?
Not in the way she'd hoped. They immediately elected the National Party and embarked on 45 years of apartheid.
And was that all?
Not exactly. In 1960, Dr Verwoerd, the South African prime minister, declared that the Queen ought to be replaced as head of the Commonwealth. That didn't happen, so he held a referendum on whether South Africa should become a republic. And then it left the Commonwealth anyway.
And what did the Queen feel about that?
Probably relief. It meant she no longer had to be Queen of a country that had been condemned for its racial policies by the United Nations, not to mention most of the remaining Commonwealth countries.
And what's she going to be doing in South Africa this time?
Oh, giving her Royal seal of approval to the new South Africa, which has come back into the Commonwealth. And it is rumoured that she wants to give Nelson Mandela a knighthood, though that could be problematical.
The prospect of having to turn Winnie into Lady Mandela. Recently, though, the palace has remarked that "if president Mandela is knighted, this will not make Mrs Mandela a Lady".
How very true. And is that the only worry on the tour?
No. The Gcakela tribe wants the Queen to give back the head of their King Hintsa. They say that in 1835 we cut it off and carried it back to Britain.
And did we?
What do you take us for, savages? We only cut off his ears. The head was somebody else's.