Hi, Allan -
I moved your message over here so people can see what has been said before. I gather from the discussion above that Josef Marais is responsible for the English translation, published in 1942.

Here's what Josef Marais says in Marais and Miranda, 1964, World Folk Songs, pp. 16-18:

In 1939 I introduced this song to American radio audiences over NBC's Blue Network. Pretoria, of course, was the important objective of the British during the Boer War of 1901, the last of the so-called "gentlemen's wars." As both sides sang it, there was no recognizable set way of performance. I wrote English verses and a definitive musical adaptation which, to my delight, has captured the enthusiasm of school and college students across the U.S.A.

-Joe-