Australia has 7 species of Parotis, and I do not know how to tell them apart. Something about a forewing black spot, but this specimen seems maybe to have traces of a dark spot on each forewing anyway.
Ian, I think Parotis marginata is the best fit. Noted in the original description, "Both wings with a marginal series of specks". Described from "Ceylon" with no work done on the Australian species, things might change.