Thanks for the reply - what we have is the following:
His daughter's name was Etla Mary Enerson, and she was married to John Reginald Whitehead. She was born between 1905 and 1914, probably 1907. So we speculate that he must have come from Norway in the late 1800's as he was 16 when he came to South Africa. Other spellings the family thinks might have been: Ennerson, Enersson, Innersan, Innersen - but he might not even have changed his name. We are quite lost as where to look - as the family does not know much either.