The Deutscher and Hackett catalogue had noted it was "only rarely that a new painting comes to light – one which has never been published" and described the artwork as a "significant discovery".
Little is known about the inspiration behind the painting, but a rural scene on Matapiro Rd has been touted as the possible source.
Angus was known to be in constant possession of a sketchbook and would make quick sketches of anything that took her eye.
Born in Hastings in March 1908, she died of cancer in January 1970, aged 62. Most of her paintings were still in her possession.
Some 620 works were deposited on long-term loan at the National Art Gallery (now the Museum of New Zealand Te Papa Tongarewa).
More than 70 of her works featured in Te Papa's summer exhibition Rita Angus: New Zealand Modernist | He Ringatoi Hou o Aotearoa, which ended on Anzac Day.