Originally Posted by bensyd

Strictly speaking the loss was automatic, it did not require Australia to do anything. In practice nothing would likely happen until it did. My mother was born in the UK to Australian parents in 1948, one year before Australian citizenship existed. She never considered herself anything but Australian. From the age of 3 until almost 50 she travelled on an Australian passport until one day she went to renew it and was informed that she was not actually an Australian citizen and would need to apply.