Buckingham Palace announced today that, as was widely expected, the Earl of Wessex will be created Duke of Edinburgh. However, the title will apparently be granted for life only, which is unusual by modern standards.
Aside from some isolated creations of life peerages in the medieval and early modern periods, the English (and later British) peerage was overwhelmingly hereditary until the latter half of the 20th century. However, the emphasis on heredity made it difficult to inject fresh talent into the House of Lords since ministers were reluctant to ennoble someone unless his family could maintain the social standards of the peerage for generations to come.
Matters reached a head in the mid-19th century. The House of Lords desperately needed peers with legal training to help with its judicial work, and in 1856, the Government advised Queen Victoria to confer a barony for life upon the jurist Sir James Parke, and he was duly ennobled as ‘Lord Wensleydale.’ But the legality of his creation was questioned, and the matter ended up before the Lords’ Privileges Committee. It ultimately held that the Crown couldn’t use the prerogative to create life peers with a seat in Parliament.
Although the Wensleydale decision left open the possibility of creating life peerages without a seat in Parliament, that wouldn’t have allowed Sir James to take part in the Lords’ judicial work. Later statutes would explicitly allow the Crown to appoint people to the House of Lords for life. At first, this power was only used to add Law Lords to the House under the Appellate Jurisdiction Act 1876, but the Life Peerages Act 1958 finally allowed the Crown to make anyone a life peer with a seat in the Lords.
However, Prince Edward’s title will not be a typical life peerage since life peerages under the 1958 Act are restricted to the degree of baron. Instead, his new title will be created entirely under the prerogative, and so it won’t give him a seat in Parliament. This would’ve seemed highly irregular in 1856, but the removal of most hereditary peers from the House of Lords in 1999 means there is now a large segment of the peerage outside Parliament.
One minor issue is that the wording of instruments passed under the Great Seal is governed by rules made under the Crown Office Act 1877. In the case of Letters Patent conferring peerages, they are contained in The Crown Office (Forms and Proclamations Rules) Order 1992. The form of a duke’s Letters Patent is set out in Form A of Part III of the Schedule. While The Crown Office (Forms and Proclamations Rules) (Amendment) Order 2000 deleted the language about sitting in Parliament from the patents of dukes, marquesses, earls, viscounts, and (hereditary) barons, the authorized text of the instrument still refers to the dignity itself being hereditary.
Some have argued on Twitter that Prince Edward’s dukedom could effectively be turned into a life peerage by instituting a remainder to the Crown. In other words, the title would technically be hereditary, but instead of descending to his son, it would go to the Crown upon his death. This might not be necessary, though. Section 2(1) of the 1992 Order states that “[f]or any document to which this Rule applies, the form of words to be used shall be that set out in the Schedule, subject only to such variations as are specified in the Schedule itself or are necessitated by the circumstances to be provided for in the document” (emphasis added). This provision arguably offers sufficient latitude to make the dukedom into a life peerage.
At the moment, it’s not clear if Prince Edward’s new title is a one-off development or part of a wider change in policy. Giving members of the Royal Family peerages for life aligns with the King’s stated preference for a smaller pool of ‘working royals’ drawn from the people closest to the Sovereign. If this is indeed part of a wider change, it would probably be prudent to amend the 1992 Order to remove all references to hereditary descent from the various Letters Patent. After all, the whole point of Orders under the Crown Office Act 1877 is to standardize the language used for instruments that pass under the Great Seal.
Finally, there is some confusion about the role of the Government in granting this title. Many people seem to think that the King is doing this entirely on his own, but that’s not the case. Even when an act is instigated by the Monarch, the Government is still involved in the process. The Prime Minister must still offer formal advice recommending that the title be conferred, while the Lord Chancellor must countersign the Warrant for the Great Seal and authorize the actual sealing. For example, when the late Queen made her husband a prince, she only did so after extensive discussions between the Palace and Whitehall.
It’s ironic that, in making his brother a duke for life, the King is using a very old power to accomplish a very modern objective. It could even have an impact outside the Royal Family. Formerly, Prime Ministers were offered hereditary earldoms after leaving office, but life baronies became the norm during the latter half of the 20th century. But it’s now been over 30 years since a former Prime Minister made their way to the Upper House, suggesting that a seat on the red benches holds little appeal for modern occupants of No. 10. Perhaps earldoms for life are the answer. Only time will tell.
 A partial list can be found in Francis Palmer, Peerage Law in England (London: Stevens and Sons, Ltd., 1907), 85-86. Other examples are in John Wallis, ed., Reports of State Trials, vol. 8, (London: Her Majesty’s Stationery Office, 1898), 515 n. b (the note actually begins on the previous page).
 Peers weren’t supposed to engage in trade or salaried work, so landholding was the main socially acceptable way for them to make money. There was also a fear that peers without sufficient means might sell their votes to Ministers. For a contemporary discussion of the importance of wealthy peers to the constitution, see Sir Nicholas Nicolas, “A Letter to the Duke of Wellington on the Propriety and Legality of Creating Peers for Life,” 2nd edition (London: William Pickering, 1830).
 The Committee’s proceedings in the Wensleydale Peerage Case can be found in Wallis, 479-722.
 He was created Lord Wensleydale for a second time, this time as a hereditary baron.
 Section 1(2)(a).
 The patents for dukes, marquesses, earls, viscounts, and (hereditary) barons all have footnotes stating that “This form may be varied as required for the insertion of special remainders or any special grants directed by Her Majesty’s commands.”
 It seems highly unlikely that anyone is going to receive a hereditary peerage.
 Similarly, the Government worked with George VI to come up with a way to deny Wallis Simpson the style of ‘Royal Highness.’ Many documents from that process can be found on the always-useful Heraldica.org.
 Harold Macmillan bucked the trend by becoming Earl of Stockton in 1984.