I have had a look since the surname "Watson" was mentioned.
I am assuming that this is them.
In 1928 Albert (A gardner) and Agnes were in Waipiro Bay, no children mentioned on the Electoral Rolls. In 1935 they were at 576 Ormond Road, Gisborne. They were still there in 1938. I have tracked Agnes through the Electoral Rolls from 1946, living at Willowpark Road, (Widow) to 1963, and found no children.
Mind you, unlike census information, Electoral Rolls may not contain children's names.
Regards
Malky