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.
List of British Jewish nobility and gentry
The British title system consists of two, sometimes overlapping entities, the peerage and the gentry. The peerage is a legal system of largely hereditary titles which is constituted by the ranks of British nobility. Under this system, only the senior family member bears a substantive title (duke, marquess, earl, viscount, baron). The gentry are untitled members of the upper classes, however, exceptions include baronets, knights, Scottish barons and Lairds.