Royal dukedoms in the United Kingdom
In the British peerage, a royal duke is a member of the British royal family, entitled to the titular dignity of prince and the style of "His Royal Highness" who holds a dukedom. Dukedoms are the highest titles in the British roll of peerage and the holders of these particular dukedoms are Princes of the Blood Royal. The holders of the dukedoms are royal not the titles themselves. They are titles created and bestowed on legitimate sons and male-line grandsons of the British monarch, usually upon reaching their majority or marriage. The titles can be inherited but cease to be called "royal" once they pass beyond the grandsons of a monarch. As with any peerage, once the title becomes extinct, it may subsequently be recreated by the reigning monarch at any time.
Peerages in the United Kingdom
Eldest sons of dukes rank after marquesses; eldest sons of marquesses and then younger sons of dukes rank after earls; eldest sons of earls and then younger sons of marquesses rank after viscounts. Eldest sons of viscounts, younger sons of earls, and then eldest sons of barons, in that order, follow barons, with the Treasurer of the Household, the Comptroller of the Household, the Vice-Chamberlain of the Household and Secretaries of State being interpolated between them and the barons. Younger sons of viscounts, and then younger sons of barons, come after the aforesaid eldest sons of barons, with Knights of the Order of the Garter and Order of the Thistle, Privy Councillors and senior judges being intercalated between them and eldest sons of barons.