RNZ called Gossage "An author and illustrator responsible for helping popularise Māori tales in schools and homes.

[2] As a child he was always interested in art, spent most of his leisure time building rafts down in Hobson Bay play fighting and mimicking military scenes.

Gossage would also study graphics part-time at the Auckland University of Technology where he "...did everything from brochures to advertisements: illustrations, typesetting, a variety of things..."[citation needed]

In 1964, Gossage traveled to Canada to study silk screening before returning home to work as a scenic artist and graphic designer at TV2.

We used a lot of Māori graphics.Gossage would work in this role for the next 10 years before catching the eye of publisher, Charles Strachan, who suggested Gossage try creating a picture book.

[3][4] In 1987, he would channel his inner child, who loved to play with model soldiers and make war dioramas, to illustrate Kathryn Rountree's New Zealand Warriors series.

John Huria, senior editor at the New Zealand Council for Educational Research said Gossage's books were: ...a gateway for many children "to the Māori visual interpretation of the stories of Aotearoa.

Gossage mentioned in an interview with a New Zealand blogger that he had never really garnered any massive criticism for his books or his retellings of Māori mythology; however, on one occasion he approached Selwyn Muru from TV2 and asked, “Can you give us any advice?” to which Selwyn then replied with, “Why don't you Pakeha leave our culture alone?” He was not a fan of a Pakeha's entire catalogue being based on Māori culture.

They met in an Auckland Hospital ward where they were being treated for mental health issues and were married in a 1971 Ratana wedding in St Mary's Bay where they wore purple, honouring each other's spirits.