Initials of given names from marriage article of son found in June 2020:
http://new-plymouth.com/pdf/feb691-15.pdf

Full given names, from New Zealand Electoral Roll - New Plymouth main Roll 1963, found in June 2020:
Rowlands, Sydney George, 20 Nobs Line, local body officer
Rowlands, Berna Olive, 20 Nobs Line, married
Rowlands, Barry Sydney, 20 Nobs Line, joiner [Son]

Year and country of marriage from search on New Zealand BDM website in June 2020:
1937/2773. Bride: Berna Olive Johnston. Groom: Sydney George Rowlands

Full date of marriage of 24 March 1937 from further searching in June 2020 on BDM Search by incrementally changing the date range for the marriage.

Year and country of death, from death search on New Zealand BDM website in June 2020:
1971/28284. Rowlands, Sydney George, died age 66Y [Therefore born circa 1905]

Full date of death of 13 February 1971 from further searching in June 2020 on BDM Search by incrementally changing the date range for the death.

Year and country of birth from search on New Zealand BDM website in June 2020:
1904/19779. Rowlands, Sydney George. Mother: Ella. Father: John Randles

Full date of birth of 12 October 1904 from further searching in June 2020 on BDM Search by incrementally changing the date range for the birth.