After the great success of Black August and the tremendous pressure of work in 1933, DW and Joan felt they deserved a break.
Accepting an invitation from Joan's brother Bino who had gone to live there, they sailed to South Africa. In Johannesburg they stayed in Bino's house, which had once been occupied by Gandhi. Thanks to an introduction, they listened to General Smuts in the House of Representatives, and among other trips they went down a gold mine and up to Pretoria.
DW was to use the material he gathered as the basis for a book about a lost diamond field. As he subsequently wrote, "Although the book sold well, I never thought much of it. One reviewer said rightly: 'Mr Wheatley should make up his mind whether he is going to write a thriller or a guide-book.'"
However the trip is notable for another reason. Either on the way out or on his return (some recent evidence suggests the former), DW had an idea for the subject of his next book ...