The current Duke of York has only male heirs.
 In Scotland, the male heir apparent to the British crown is always the Duke of Rothesay as well, but this is a dukedom (title) without a duchy
 A duke may or may not be, ipso facto, a member of the nation's peerage: in the United Kingdom and Spain all dukes are/were also peers of the realm, in France some were and some were not, while the term is not applicable to dukedoms of other nations, even where an institution similar to the peerage (e

