I was to spend the hour in the bricked-in quadrangle of the women's section of the brick and bar monster that is Marshall Square. Part of the building goes back to pre-Boer War days. The plumbing pipes are all external and they lace the walls of the quadrangles like a corset of iron trellis. Water and sewage pipes gurgle and splutter and flush up and down the two storeys and this little exercise yard is an excellent point from which to plot an ablutions graph for the white prisoners’ cells. The few steps out of the cell were like a hurtle through space on a funfair figure of eight, and my stomach leapt as my legs moved across the concrete threshold. But the exercise yard was too like a cell. The sky was trapped by brick walls extending upwards and, like the warders regulating my stay in the courtyard, the brick walls officiously limited the shine of the sun. There was nothing for it but to walk round and round the courtyard.

On chill days I loped but tried to put out of my mind the thought of generations of prisoners doing the same. On sunny days I basked in the patch of sun, moving with it, if I could stay long enough, as it inched westwards across the courtyard and then out of reach.

There was another exercise yard for the women but it was used for men detainees until the women wardresses reasserted their, or our, claim. This was a sandy yard, four times the size of the women's quadrangle, deep in the bowels of the station and closed in by fourteen-feet-high brick walls, with mesh on top. To see what lay beyond the walls I stood in the pit of the quadrangle with my head thrown back. Then like a victim in the gladiators’ den I could see and be seen by the elevated spectators, in this case the skyscrapers of Johannesburg's mining and finance houses. Marshall Square lies in the heart of the multimillionaire concerns mining South Africa's gold and diamonds: The new Chamber of Mines building is a stone's throw away.