Here is an image of Arthur Conan-Doyle in the Watervaal escape tunnel and accompanying quote from his "Memories and Adventures" published in 1924.
"Our longest excursion from Pretoria was to Waterval, whither Bennett Burleigh took me in his Cape cart. Once we got quite close to a Boer patrol, about a dozen horsemen. Burleigh could not believe that they were actually the enemy until I pointed out that several of the horses were white, which was hardly ever known in our service. He then examined them with his glass, and found I was right. They were clearly on some quest of their own, for they took no notice of us, though they could easily have cut us off. Our drive took us to the great prison camp where so many British and Colonial soldiers had a humiliating experience. The prisoners had only got free a week or two before, and the whole place, many acres in size, was covered with every sort of souvenir. I contented myself with a Boer carbine which had been broken by a British prisoner, a band triangle, a half-knitted sock, the knitting needles being made from the barbed wire, and a set of leg fetters from the camp gaol. A tunnel had been bored just before the general delivery by some captive Hussars. It was a wonderful work, considering that it was done chiefly with spoons, and it had just been finished when relief came. I descended into it, and was photographed by Burleigh as I emerged. I daresay many of my friends have copies of it still, with my inscription: “Getting out of a hole, like the British Empire.”
I had seen a similar image with a soldier published in Black and White Budget Magazine, but not this image with Conan-Doyle.