Thanks for this posting Tony. I puzzled over the Snowy-mint-bush at this location about 15 years ago, and then forgot about its existence. From memory there were only three plants present then. I think it is most likely a garden escapee, or spreading from a planting, but given that this plant grows apparently naturally at Burrunjuck and Monga National Park, a natural occurrence on Red Hill may be a possibility.
Geoff Butler do you know whether or not the nurseries sell a recognisable cultivated form?