Thanks for the extra information, David. A death cert is usually less reliable than a marriage one, because the "informant" may have guessed or only vaguely remembered what he/she had been told.
Do you know who the informant was on his death cert?

For a marriage cert the information is given by the couple themselves, so is usually far more reliable. Unfortunately the parents and other details are only given on NZ marriage certs from 1880, so John's one is too early to have that information (unless he had a second marriage?).
However, if any of his children's birth certs were after 1876 they should have father's (and mother's) name, age, occupation, and birth-place.
Please tell me what any child's birth cert after that date has for him?

Sue