This is where your post on the SA board should come in handy - we need help from some experts on things like the contents of death certs in SA and naturalisation records - maybe he told more on the latter? Also the shipping records - to see whether he travelled alone. Also his occupation might help pin him down in the UK.
I have added a link to this thread on the South Africa thread.

p.s. red message - Rafter just posted some likely shipping records!
(incidentally - why did you give 1929 as the earliest date for the marriage?)