Dukes in the United Kingdom
Duke, in the United Kingdom, is the highest-ranking hereditary title in all four peerages of the British Isles. A duke thus outranks all other holders of titles of nobility (marquess, earl, viscount and baron).
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.