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).
Hereditary peer
The hereditary peers form part of the peerage in the United Kingdom. As of 2016 there are 820 hereditary peers. The numbers of peers – of England, Scotland, Ireland, Great Britain, and the UK – whose titles are the highest they hold (i.e. are not subsidiary titles) are: dukes, 24 (non-royal); marquesses, 34; earls, 193; viscounts, 112; barons, 445.