Year and country of birth from search on New Zealand BDM website in February 2021:
1905/4922. Oliver, Robert William Hamilton. Mother: Mary Julia. Father: William Alfred

Full date of birth of 4 March 1905 from further searching in February 2021 on BDM Search by incrementally changing the date range for the birth.

Year and country of marriage, from search on New Zealand BDM website in February 2021:
1928/9928. Bride: Elsie May Ford. Groom: Robert William Hamilton Oliver

Full date of marriage of 20 June 1928 from further searching in February 2021 on BDM Search by incrementally changing the date range for the marriage.

Name confirmed in two emails dated 18 January 2021 from Mark Oliver where he writes, "I was at function yesterday for my father, Grant Arthur Oliver, son of Robert William Oliver" and, " young Bob, my late Grandfather died early 1980s, spent some in Australia….”. “Eventually he came home and took up farming over Matata way, where my father [Grant] grew up.

In a followup email dated 22 February 2021 Mark writes, "my grandfather Robert William Oliver was from that first marriage".
Mark is the grandson of Robert William Hamilton Oliver.

Year and country of death, date of birth confirmed, from death search on New Zealand BDM website in February 2021:
1986/53931. Oliver, Robert William Hamilton. Date of birth: 4 March 1905

Full date of death of 8 February 1986 from further searching in February 2021 on BDM Search by incrementally changing the date range for the death.