It puzzles me why he never became a citizen. He moved to the UK in 1966, that's 54 years now, and it was even before they joined the EEC sometime in the 1970s.
Doing so before 1992 (or as late as 2001 if notification requirements were not complied with) would have lost him his Italian citizenship, unless an exception applied. I can understand being satisfied with a stable situation for most of that time, and with not wanting to handle naturalization paperwork in the last decades of life.
Good point. I somehow assumed EC citizens would be exempt from such laws but that doesn't necessarily seem to be the case even now [1], and must have been very different before the 1992 Maastricht treaty indeed.
It's possible to like living somewhere and be comfortable with permanent residency, but to have compelling reasons to retain the citizenship of your birth country. Many countries require that you give up the old citizenship when you get a new one.
In my case, Germany requires citizenship applicants to show proof that they have attempted to give up their original citizenship, unless it's another EU country, and that's only because the EU high court ruled that they have to let EU citizens retain their EU citizenships.
I love living in Germany, have learned the language, contribute a lot to it and will probably live here the rest of my life, but I'm an American and have no intention of giving that up.