So, i was wondering how, and if, you should include 'of' when speaking somebody's last name, especially if it is in a foreign language. e.g: John of Gloucester Jacque de Troyes Would you say 'of Gloucester' or 'Gloucester' in a phrase like this: "XX says that turnips are blue." And, would this still apply in foreign names? Such as french (de) or german (von) (or any other language)? I asked this because families like Hapsburgs where called "von Hapsburg", yet in many texts they are referenced as either "Hapsburgs" or "Von Hapsburg" or "von Hapsburg" in a seemingly interchangeable fashion. Then, you have last names that are almost uniquely said with the "von" or equivalent, but some, primarily with English names, are said almost always without. Anyone got any clarification?
Some of the difference is simple vagary and shift in any language, and some has to do with whether a name solidifies with a prepositional particle as a convention. In your example, Jacque de Troyes is a nobiliary particle and is different to a solidified surname like Martin De la Rúa. It's not the same thing. There is a lot of overlap and inconsistency, though, as you have already noted. The line between nobiliary particle and prepositional particle as part of a surname is fuzzy, and the former has a habit of evolving into the latter. https://en.wikipedia.org/wiki/Nobiliary_particle
I see, so I take it there isn't any conventions as to whether one should, or should not, include the "of". I have seen many [scholarly] papers where typically when this occurs where the author uses only the last name if it is an English name. However, they include the preposition when the name is of a foreign origin. I assumed this was because saying within a sentence such as "of Dusseldorf says....." sounds less proper than saying it with the german preposition "von Dusseldorf says..." or without any preposition "Dusseldorf says...". But it seemed interchangeable and wondered as to the reason one should omit, or include, the preposition simply because it is of a different language.
