Looking for information on Isidore van der Wath

Graham Acheson. Steytlerville, Eastern Cape

We have just lately in the last few years learnt that she gave birth to a son called Isidore after being released. We have reason to believe that the father was the owner of The Bridge Hotel or a shopkeeper in Aliwal North. 

None of the family were ever told about the father as she was sent back to her family in Thabanchu in disgrace.

The boy was called Isidore van der Wath (maiden surname of great-granny) and at one stage he was secretary to South African Prime Minister Jan Smuts.

We are just assuming that she named her son after the father as Isidore is rather an unusual Afrikaans name.

Finding out anything about my great-grandfather would be for family tree purposes only.