Hello Mick,
When your grandfather was born that area was Italian.

This is an excerpt from an online encyclopedia:
Assigned to Italy from Austria-Hungary after World War I, at the end of World War II it was part of the Zone B of the Free Territory of Trieste, controlled by Yugoslavia. Most of the ...

My grandfather Romano Viller came to Australia in 19454 for work as a cane cutter, and all he ever said was he was Italian, which I'm unsure about as after he died I found the extract of his birth certificate which said he was born in Slovenia and led me to scratch my head but it did give me limited ...