Hi David, I am guessing that you had one of the older trees. These trees would be 3-4 years old now. They may have experienced -5 degrees c on the nursery in Queensland so they should be fairly hardy but to be on the safe side I would use some fleece which can be purchased at Garden Centres and protect it from the worst of the frost this year. You may find that the foliage will go a bronze colour in the frost. This may persist through to the spring when the foliage will turn back to its normal green colour.