Doak was sure the portrait, attributed in auction to "the New Zealand School", was indeed an original painting by renowned artist Charles F Goldie.
Since then, Doak, who is based in Christchurch, has been on a mission to prove the painting's significance and reconnect the portrait's subject with his history.
Doak believes this portrait could be of a significant Te Arawa koroua. Photo / Supplied
"This is a painting that has been lost in obscurity for a hundred years," Doak said.
"There wasn't any doubt [for me]. I looked at it purely in the light of day and I thought it was something more than what it was purported to be. It was a gut feeling.
"I wanted to bring it back to New Zealand. I felt it was important."
Goldie was born in Auckland in 1870. After studying art in Paris he returned to New Zealand, where he died in 1947.
Goldie remains best known for his portraits of koroua and kuia. His first painting of this kind was of Rotorua's Mary Wharepapa in 1902.
Doak believes the portrait he bought could be significant for the people of Te Arawa.
His first clue was in the portrait's frame, where Doak found a label and an exhibition number.
A signature in the corner of the painting and labels found on its frame could point to this being an original Goldie. Photo / Supplied
"The label was from the frame-maker of Charles Goldie," Doak said.
"The signature is consistent [with] Charles Goldie. The exhibition label [number 15] was for 1917 and the frame was an original of the era."
Doak's research discovered that Goldie had exhibited a painting entitled Lost in Thought, Ngaheke, an Arawa Chieftain in Christchurch in 1917. The portrait was number 15 in that exhibition.
"How could it not be?" Doak said.
Doak brought the painting to retired curator and owner of Independent Art Valuations Ltd Neil Roberts.
Roberts had been a curator at Robert McDougall Art Gallery and the Christchurch Art Gallery Te Puna o Waiwhetu for 27 years.
"There were certainly areas of the painting which were clearly by Goldie's hand," Roberts said.
"That's what convinced me that it was originally a Goldie."
Roberts said at first he'd had some reservations because the painting had undergone "substantial cleaning and reconstruction" in its lifetime.
"But then, I looked at it closely.
"Goldie had a quality of being able to lift the texture of the face out of the picture frame to a degree."
An exhibition catalogue from 1917, showing two portraits by Goldie were on display. Photo / Supplied
Roberts said he could see these qualities in the painting Doak had purchased and that the painting was the right age as well.
"I've seen many works over the years. You get a sense for whether or not a work is genuine.
"So you start with that and then you try to prove yourself wrong."
Roberts has given Doak a letter of authenticity saying to the best of his professional knowledge, the portrait is a work of the artist, Charles Frederick Goldie.
Independent Art Valuations Ltd estimated the insurance value of Doak's painting at $455,000.
The record sale price for a Goldie portrait at auction was set on Tuesday night when the portrait of Kamariera Te Hau Takiri Wharepapa sold for $1.8 million.
The previous record was set by Hori Pokai - A Sturdy Stubborn Chief, which was hidden for 100 years before it sold for $1.7 million in November.
The artist Charles F Goldie in his studio, digitally recreated. Image / Supplied
Both record-setting paintings were sold by Auckland's International Art Centre, the country's most experienced fine art auction house.
The centre's director Richard Thomson said at this stage it would not handle Doak's painting for its own reasons.
Doak said he was more interested in learning about the subject of the portrait.
"I just want the story completed. I want to know who this man is, where he is from and what his name was."
Doak said he had spoken to the curator of Pacific arts at Australia's National Gallery.
"[I was told] his moko could suggest he was a chieftain or someone of very high standing and the panel of markings to the side of his head would tell us much more if they were replicated accurately by Goldie."
Doak said he hoped that bringing the painting to the public's attention might help him to discover members of the chieftain's family.
When asked if he thought the painting could indeed be of a Te Arawa koroua, Rotorua Museum chairman Monty Morrison said anything was possible.
"At first glance, it looks like he could be of Te Arawa descent. Regardless, the finding of this work is certainly an exciting development for his whānau and descendants.
"It would be good to set an assessment from our own art historians and whakapapa experts."
