I agree that casting is a problem when the younger and older representations of the same character don’t match in a visual sense. It is also a specific problem in South African films. There have been too many British and American actors in roles that could have gone to local actors. However, in this case, as I’ve indicated in the posting, I suspect that Sophie Okonedo’s presence helped first get the film’s budget confirmed and then helped the film get sold to distributors. If there are no professional actors locally who fit the bill, casting a non-professional actor is not always a good option either as it can make the production more difficult or more expensive to organise.

I did see the BBC documentary The Search for Sandra Laing [as I remember the title]. it must have been broadcast sometime in the early 1980s.