From Muriel Leo’s (nee Oliver, 1917-1998) Family Tree.
Date of birth, and second name, from Colin’s wife, Joy (Margaret Joy) Nixon - nee Oliver, daughter of Leslie John Oliver.

Date of death from Anita Nixon, grandaughter of Colin Nixon here.

NIXON, Colin Robert On 12 June, 2016 passed away peacefully at Radius Taupaki Gables, aged 90 years. Dearly beloved husband of the late Joy, for 65 years. Dearly loved father and father-in-law of John and Lynette, Noel, Rex and Delwyn, and the late Geoffrey. Cherished Granddad of Trevor, Anita, Lisa, Sheree, Andre, and the late Kerry. Loved great granddad of Elle, Lola, Jaimee, Sienna Jack, Alexis, Leo and Quinn. Rest in peace Dad, Granddad and Great Granddad. Thank you to the staff at Radius Taupaki Gables for their wonderful care of Colin. Colin's farewell will be held in the Main Chapel of the Morrison Funeral Home, 220 Universal Drive, Henderson on Thursday, 16 June, 2016 at 12:30 p.m, followed by interment at the Kumeu Cemetery, Kumeu. All communications to the Nixon family C/-the above Funeral Home.
Published in The New Zealand Herald from June 13 to June 14, 2016

Year and country of marriage from search on New Zealand BDM website in June 2023:
1947/10630. Bride: Margaret Joy Oliver. Groom: Colin Robert Nixon

Full date of marriage of 18 July 1947 from further searching in June 2023 on BDM Search by incrementally changing the date range for the marriage.