[1][2] She studied portrait painting under the noted Australian painter Antonio Dattilo Rubbo (1870–1955)[3] during which time she also began writing and drawing comic books for her own amusement.
"[4] Jo was a beautiful raven-haried dancer who, with the aid of her magic cape, to assist her American fighter pilot boyfriend, Serge Shawn, to outwit gangsters and the Japanese.
[6][7] The strip quickly established Bertram's reputation as a vivid and imaginative cartoonist, her work characterised by her granite-jawed heroes and voluptuous, glamorous women.
According to Kevin Patrick, Bertram was "Unlike many of her male counterparts of the time," and "from the outset grasped the dynamic storytelling possibilities of the comic book page.
Huge panels, inventive compositions and dizzying perspectives dominate her page layouts (many of which were prepared by her sister, Kathleen), while her use of over-the-top sound effects anticipates the comic book paintings of 1960s 'Pop' artists like Roy Lichtenstein.