Thanks to Alan Taylor, renown South African aviation historian, the full results and exclusions of the 1937, 1938 and 1939 Governor-General's Cup have now been published on this site.
Alan has also written a short biography on Roy Coull, the winner of the first Race. This book, titled OF MOTHS AND MARAUDERS, is available on the internet.
It was interesting to note that the pilots that did not do well in the 1937 Race were unhappy with the handicap system. Looks like nothing has changed in 70 odd years.