Three paintings bought by a young female law graduate in the 1960s could deliver a $1 million-plus windfall for the Auckland Art Gallery Foundation.

The works by Colin McCahon, Don Binney and Richard Killeen will be auctioned in August by Art+Object, with all proceeds going to an endowment fund administered by the philanthropic platform that supports Auckland Art Gallery Toi o Tāmaki.

The trio of paintings (with a combined top auction estimate of $1,025,000) have been donated for sale by Queensland-based Dr John Mayo. They were all purchased by his late wife Marylyn, soon after she became one of the first women to graduate from Auckland Law School.

Mayo doesn’t know how much his wife originally paid for the works but says while she would have been familiar with McCahon (her mother Mavis Mason was an artist mentored by the famous painter), Binney and Killeen were relative unknowns when she made her purchases at Barry Lett Galleries.

“Whether it was advice from Barry Lett, or whether she found the pictures appealing ... it happens that she chose two artists who have become very well known.

“They were just getting established when she bought them.”

Don Binney’s 1966 painting Summer Fernbird (inscribed “Te Henga”) is the most valuable of the three donated for auction, with an estimated worth of $400,000-$600,000. It has a larger counterpart in the Auckland Art Gallery permanent collection but, in that example, the bird faces in the opposite direction.

Waterfall by Colin McCahon (1965) is one of three works donated by Dr John Mayo to an Auckland Art Gallery Foundation fundraising auction.

Colin McCahon’s Waterfall has an auction estimate of $250,000-$350,000 and Richard Killeen’s Man, Land and Sky is expected to fetch between $55,000-$75,000.

All three paintings have hung in the Mayo home in Australia for decades.

Mayo, who met his late wife when he shifted across the Tasman to lecture in law at Townsville’s James Cook University, says “her interests are now my interests ... she fostered the love of art for me”.

And, while he says he “very much” liked the Binney, he admits it took longer to fully appreciate the McCahon and Killeen.

“The McCahon was a waterfall. I had to have it explained.”

John and Marylyn Mayo are life benefactors of the Auckland Art Gallery Foundation and the gallery’s member’s lounge is named for them. Their philanthropy includes the Marylyn Mayo Internship programme and a chair at Auckland Law School.

“The art gallery is very central to the cultural life of any city,” Mayo said this week. “Just like libraries, theatres, the philharmonic, the museum ... there are a lot of art things that need support from the public, alongside what they get from the council.”

Man, Land and Sky is a 1968 painting by Richard Killeen that will be auctioned in an August fundraiser for the Auckland Art Gallery Foundation's endowment fund.

Penny Deever, Auckland Art Gallery Foundation manager, says the donation sets a model for the future.

“Donors can now help us by gifting artworks that are first offered to the Gallery collection. If the works don’t meet the criteria set out in the Gallery’s acquisition policy, they can then be offered to the Foundation for sale, with the proceeds benefiting the Gallery.”

Projects supported by the Foundation’s endowment fund have included exhibitions, education programmes and conservation work, a programme for emerging curators to work alongside senior staff, and the operation of the EH McCormick Research and Archive library.

The Mayo paintings will headline Art+Object’s August 19 important paintings and contemporary art auction.

Ben Plumbly, director of art, says the sale is a “rare opportunity to acquire unique and significant examples from the 1960s of their respective practices, while supporting Auckland Art Gallery Toi o Tāmaki’s ambition and excellence”.

Other gifted works confirmed for the endowment fund section of the auction include pieces by Max Gimblett and Fiona Pardington.

Kim Knight joined the New Zealand Herald in 2016 and is a senior reporter on its lifestyle desk.