I found this group of caterpillars on the underside of a branch in Potoroo Palace. The only butterfly I saw in the same area was a large citrus but these don’t look like citrus caterpillars.
That resembles the larvae of some Epipaschinae, like http://lepidoptera.butterflyhouse.com.au/pyra/pyrastis.html @RossMannell : can you rear a couple to get an adult moth for identification of the species ?