I notice a marriage in freebmd for a William Henry Christian to a Jane Wilson 1873 with subsequent children Martha Jane and Robert Edward.

Rootsweb shows an enquiry in the South Africa Archives from Jean Henderson, which also shows her E-mail address, the gist is as follows:-

Robert Edward Christian emigrated from Whitehaven to New Zealand with his parents and sister. They arrived at Port Chalmers 29 Jan 1887.
The parents and Robert went to Greymouth South Island.
Robert died in Johannesburg 5 Feb 1958.

Len Faragher