My father was a resident of France in 1984. He has since passed away. My uncle told me that it was possible that my father acquired French citizenship as both he and my father resided there for a long time. I'd like to check if that may have actually been the case. I have my father's date of birth and his Sri Lankan passport number from his old passport issued while in France. Now I'm in London. Could I inquire with the French embassy about my fathers details? Would they have a record of my father's citizenship if he indeed had such?
The French embassy in London probably does not have the record for an acquisition of French nationality that happened in France.
They nevertheless may have some clues on how to conduct such a search. So you can call the French embassy, unless you have some undisclosed reason not to do so.