who is john harrison, and how does his relationship with his father mirror Arthur Jarvis's relationship with his father?

The brother of Mary Harrison, the wife of Arthur Jarvis, John meets James and Margaret Jarvis at the airport and helps the Jarvis family during their stay at Johannesburg. John Harrison holds much more liberal views than his father concerning the status of blacks in South Africa. Before leaving for home, James Jarvis gives John Harrison a check for ten thousand dollars and requests that he start the Arthur Jarvis club promoting social work in South Africa. Arthur Jarvis also had very liberal views that his father didn't agree with. This question extends through the book.