There’s not much that Kate Mulvany doesn’t know about author Ruth Park and her Harp in the South trilogy. Mention any character or incident from any of the three novels and she will instantly know the reference, in minute detail, and have something wonderful to say about it.

“I think I know them off by heart, down to the page number,” she says with a laugh. “It’s a pretty big tome but worth it, and every time I go back into it, I find something new that surprises me. [Ruth Park] was an absolute genius and treasure of a writer.”

Mulvany has spent the last three years getting closely acquainted with Park’s books about the Irish-Australian Darcy family, set in Sydney’s squalid Surry Hills long before gentrification, in order to adapt them for the stage. Immersing herself in The Harp in the South, first published in instalments in The Sydney Morning Herald in 1947, its darker sequel Poor Man’s Orange published in 1949, and a prequel called Missus published much later in 1985, she has lived and breathed them, falling in love with the “fabulously flawed” characters, who she says, “lifted me and...