411A,
Domestically, there has never been a legal age limit in Australia, as opposed to airline/union imposed limits.
However, the medical start to get very stiff after 60, now even for a PPL. Unfortunately, too much depends on the subjective judgment ( which should be objective) of certain medicos, the latest CASA head of Aerospace ( why Space, I wonder??) Medicine has very rapidly become known as Dr. No.
I don't know of any pilots over 70 still flying for major carriers, but there are certainly pilots over 70 flying for small non scheduled operators.
Tootle pip!!