Her father, Walter Kirkpatrick Thompson, was a builder, and her mother, Marie Gabrielle Buffett, was a piano teacher.
Thompson was born with haemolytic disease of the newborn, and her life was saved with a full blood transfusion immediately after birth.
In 1960, she worked as an illustrator for the New Zealand Herald while studying part-time at Elam School of Fine Arts.
She left Elam without finishing her degree out of protest after McCahon told her that she would never be a true artist because motherhood would distract her.
[1] In a 1965 exhibition Thompson presented a series of large, mostly abstract paintings, wanting to create "environmental art which confronts [the audience]".
Late in the decade she began her "Cycle" series, featuring symbolic paintings centred on stylised palm trees.
Her "Plains and Volcanoes" series, exhibited in the early 1980s, juxtaposed realist landscapes with dream-like environments.
Thompson's 1997 series, "Tuki and Huru", followed the story of two young Māori men kidnapped in the 1790s to teach flax weaving to convicts on Norfolk Island.
She noted that critics often discussed her work in relation to her domestic life, which they didn't do for her male peers.