Her father's dukedom was granted by the king of France in 1775
(confirmed in 1817), and he did in fact also hold two Roman princely
titles, granted, however, in 1823 and 1911. (The second title was
granted to the present duke's ancestor who was the son of a younger
son, and whose line only inherited the dukedom and the elder Roman
title in 1940). The Clermont-Tonnerre family had helped the papacy once
before, expelling the antipope Gregory VIII from Rome; that is the
reason traditionally given for their arms (gules two keys in saltire
argent).