The 1920s were a fascinating  time in black SA politics and still very under-researched.  
For me the story of the ICU union and Clements Kadalie is particularly moving -- at one point he was running a 100,000 strong black union which had blocked Cape Town harbour in 1919, being threatened with deportation to Malawi by the SA government, and fighting both the right wing dominant faction in the ANC which thought he should concentrate on change through mixed tennis leagues and the radical bolshevik left which wanted full on confrontation.
All with out moaning and good humour.