"His conduct and demeanour during his time in the public eye offers great examples of service to the country and the community, and a commitment to doing what's best for others.
"And it is superb to see him remembered in the way he is with this exhibition by the people of the region he represented so well.
"This event is a special one because it's about community - and there's a nationwide element to it.
When asked if he could imagine a politician leaving office to a fight in a world war in this day and age, Sir Mateparae said: "No I can't because I don't want there to be another world war." Also at the opening was Mr Coates' oldest living relative and niece, Coreen Patterson.
The 95-year-old lifetime Matakohe resident, who is one of the longest serving volunteers at the Kauri Museum, was elated to have her uncle celebrated with the exhibition, and opened by the Governor-General. "Naturally, it was an honour," she told the Northern Advocate.
Mrs Patterson could not pinpoint her favourite memory of Mr Coates, who died in 1943. "They're many. I just always enjoyed spending time with him."
The exhibition included items such as Gordon's sheep medals, Silver Spade, jewellery, a typewriter, as well as records such as cheque books and accounts.
Kauri Museum chief executive Lisa Tolich said the exhibition had taken two years to collate, after it was spearheaded by her predeccesor Betty Nelly. "Gordon Coates is a local celebrity in the area," she said.
The Otamatea Kauri and Pioneer Museum Board received support for the exhibition from the Coates family, Lottery World War I Commemorations - Environment and Heritage Committee, ASB Community Trust, Heritage NZ and Pouhere Taonga and Ministry for Culture and Heritage.
Sir Mateparae was in Northland on a two-day visit, which included awarding two Queen Service Medals, and hosting a dinner for regional mayors on Thursday.
When asked what his favourite part of the trip was, he said:
"I have no favourite part, I think just coming up to the North and being able to meet with people and celebrate the things that happened in the past as well as things happening now."
Sir Mateparae presents QSMs, page 5