The red dorsal glands on the penultimate segments suggest, Lymantriinae, and it is similar to larva of Euproctis aliena at http://lepidoptera.butterflyhouse.com.au/lyma/lyma-cats.html but the head capsule seems to be the wrong colour, so it may be one of the other 51 Australian named species in Lymantriinae for which no larval photos have been published. @clarehoneydove : it would be really good if you could take it into protective custody, and rear it to get the adult moth to ID the species ?
@donhe it is in protective custody after being absolutely hammered by a storm here and hanging onto the same branch. Never reared a moth so doubt it will make it.
I use glass jars with a piece of muslin held on with a band (rather than a lid) and it the survive to later instars I have plastic containers from the petshop. The trick is finding what they will eat and keeping up the supply.