Ben Plumbly from A+O explains:
"The most a Gordon Walters painting had previously sold for was $430,000 and that was four or five years ago," Art & Object auctioneer and director Ben Plumbly said. A retrospective exhibition of Walters' works titled New Vision was recently displayed in galleries around the country and finished at Te Papa.
"I think his work is increasingly admired and for us in art market the way he painted means his works are extremely rare. He could take seven years to finish a painting. So it's a pretty major piece." from the Stuff article here.
This work was purchased from Webb's in 1989, I was unable to trace the hammer price for this auction.