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.
History of the British peerage
The next major event in the history of the Peerage occurred in 1707, when England and Scotland united into Great Britain. There were, at the time, one hundred and sixty-eight English peers and one hundred and fifty-four Scottish ones. English peers did not wish for their individual significance in the House of Lords to dwindle, so they agreed to permit Scotland to elect just sixteen representative peers to sit in the House of Lords (see Parliament and the Peerage). After the Union, creations in both the Peerage of England and the Peerage of Scotland ceased and all new peerages were created in the Peerage of Great Britain.