Associating nobility with gold belts apparently dates back to Roman times. Gibbon (124) mentions that in the time of the Emperor Constantine military commanders called dukes and counts were distinguished by gold belts. Even today a “gilded youth” is defined as a young man of wealth and fashion (75). That definition could as well apply to dukes, even old ones. Dukes, earls, and other noble titles are comprehensively dealt with under “Characters” in Iolanthe.
Fled gilded dukes and belted earls before me