"They love McCahon's work."
They also had "an association with the Waikato", which was one of the reason's they were interested in that particular artwork.
The couple, who Gow thought were in their 50s, own several properties throughout the country and "spread themselves" around, but Auckland was where they called home.
Gow works as an agent on behalf of the couple, and has bought a number of artworks on their behalf in the past.
"That's what we do as part of our job."
The Canoe Tainui set the record on Wednesday for the most expensive painting sold at auction in New Zealand.
Art auctioneer Ben Plumbly said the piece "may well be the most important painting to come on the auction market perhaps ever".
"Isn't it fantastic Colin McCahon will hold that record."
It was sold at the first of two auctions consisting of 481 works from the late Tim and Sherrah Francis collection.
The Canoe Tainui was purchased in 1969 for $550 and was expected to go for between $1.2m and $2m at the auction.
Previously the most expensive painting sold at auction in New Zealand is Charles Frederick Goldie's A Noble Relic of a Noble Race. That went for a total price, including buyer's premium and fees, of $1,337,687 in April.