Her best known works are the novels The Harp in the South (1948) and Playing Beatie Bow (1980), and the children's radio serial The Muddle-Headed Wombat (1951–1970), which also spawned a book series (1962–1982).

[6] Park's first break as a professional writer came when she was hired by the Auckland Star newspaper as a journalist, but she found the assignments she was given unchallenging.

Wishing to expand her horizons, she accepted a job offer from the San Francisco Examiner, but the tightening of United States' entry requirements after the bombing of Pearl Harbor forced a change of plan.

[6] (Park was devastated when Niland died in Sydney at the age of 49 from a heart ailment; Kilmeny also predeceased her — see the Herald obituary.)

When contracted in 1942 by Ida Elizabeth Osbourne to write a serial for the ABC Children's Session, she wrote the series The Wide-awake Bunyip.

When the lead actor Albert Collins died suddenly in 1951, she changed its direction and The Muddle-Headed Wombat was born, with first Leonard Teale then John Ewart in the title role.

Even though it was acclaimed by literary critics, the book proved controversial with sections of the public due to its candour, with some newspaper letter-writers calling it a cruel fantasy because as far as they were concerned, there were no slums in Sydney.

However, the newly married Park and Niland did live for a time in a Sydney slum located in the rough inner-city suburb of Surry Hills and vouched for the novel's accuracy.