Hi JM,
My grandfather's Certificate of Naturalisation was issued on 22 December 1902, the condition being he had resided in New South Wales for 5 years and intended to keep residing there, The Certificate was issued by the NSW Government under the Naturalization and Denization Act of NSW, 1898.
Andcarred
Yes, that would make him, his wife and any of his children aged 16 and under, naturalised British Subjects ...
I am confident that law would be readily available via google .. It may be under 16 years, rathet than 16 and under ... the residency requirement for NSW 1898 was 5 years ...
There are actually still some statute Colonial NSW laws that are still current,

JM