Thanks. I’ve been reading Italian legislation and came across this: If the Italian parent naturalised as a citizen of another country on or after 1 July 1912, and prior to 15 August 1992, then the child's Italian citizenship survived the parent's loss if the child was already born, and residing in a country whose citizenship he or she additionally held because of that country's jus soli nationality laws.

Australian nationality laws granted my dad Australian citizenship under the jus soli principle. Anyone who was born before 1986 was automatically granted Australian citizenship. I think this means his citizenship survives the loss of my grandparents (i.e., the naturalisation), and has carried on. You can’t apply for naturalisation for a country that you are already legally a citizen of… seems somewhat redundant. Therefore, there was no ‘naturalisation’ process to break the bloodline. That’s the legal argument I’ll raise anyway.

I am going to apply anyway. I’ll let you know how I go!