Most peerages are hereditary, meaning that they pass on from father to son, or to another heir.(25) (Some peerages are created only for life, and cannot be inherited.(26)) They cannot be willed or bequeathed; how a peerage is disposed is determined by the terms of the original creation of the peerage.
A peerage passes from father to son, but sometimes a peer dies without a son to succeed him. For example, the 6th Duke of Devonshire (1790-1858) never married. When that happens, go back one generation, to the peer's father, in this case the 5th Duke (1748-1811), and trace the next eldest male direct lineal descendant. In this case, that would be 5th Duke's other sons, if he had any. He didn't (at least, not a legitimate one), so we go back one more generation, to the 4th Duke (1720-1764). The 4th Duke had at least two sons: William, who succeeded him as 5th Duke, and Lord George Cavendish (1754-1834). Lord George died during the 6th Duke's lifetime, but if he had survived him, he would have become the next duke. However, he left a son, Mr. William Cavendish (1783-1812), who also died before the 6th Duke, but left one son, Mr. William Cavendish (1808-1891). This man became the 7th Duke of Devonshire.
But if Lord George's line had died out, then the dukedom could be traced back up to three more generations, all the way to the 1st Duke, and descend through the eldest of his other sons who had surviving legitimate male issue. If there was no legitimate surviving male descendant, then the title of Duke of Devonshire would become "extinct." However, if there was a legitimate surviving male descendant of his father, the 3rd Earl of Devonshire, then that person would inherit the earldom. In this way distant cousins can sometimes inherit lesser titles while the highest peerage dies out.
What's most important to remember is that if a man inherits a peerage, it is because he is the eldest surviving legitimate male who can trace a direct (father to son) lineage back to an earlier holder of the peerage. In other words, he doesn't inherit because he was the brother or the cousin or the uncle of his predecessor, but because his own father, or grandfather, or great-grandfather, or great-great-grandfather, etc., was an earlier holder of the peerage. ["Eldest" in this context doesn't mean that he happens to be the oldest of several different living men who can trace a direct line back to an earlier holder of the peerage, but rather that his line is the eldest, i.e., eldest son of eldest son; all other lines senior to his have died out.]
There are three types of peerages. The first, and most ancient, is a peerage held by writ, which is a direct summons by the Monarch to attend the Parliament; the second is Letters Patent, which institutionalized the writ and ensured successors of the right to attend Parliament; the third is by tenure (a pre-Parliamentary barony by tenure -- now considered non-existent).(27)
Peerages by writ are almost all baronies, because none of the other titles were invented then (except earls, which then were exclusively sons or cousins of the sovereign).(28) The ones which survive are naturally the most ancient titles. A writ entitled the peerage to pass to the "heirs general," not the "heirs male" as specified in almost all Letters Patent peerages.(29) (For more about how women can inherit ancient peerages by writ, see the section on Peeresses.) Occasionally, a peerage created by letters patent allowed a special remedy so that the peerage could pass to a brother or even a daughter if the new peer had no male heir.(30) A famous example of this is the 1st Duke of Marlborough, whose dukedom was inherited by his eldest daughter.
The following explanations of attainder and extinction were contributed by John Hopfner:
There are two ways that a peerage can end, or become "extinct."
The first is "by attainder," which is what results when the sovereign gets really, really upset with a peer, and revokes his peerage: this happens for offenses such as unsuccessful rebellion against the crown. An example is the Duke of Suffolk, whose peerage was attainted because he placed his daughter, Lady Jane Grey, on the throne as Queen in 1553 (and of course he lost his head as well as his peerage).(31) Sometimes the descendant of an attainted peer, or the peer himself, manages to win back the favor of the crown and have his peerage restored, as did the Dukes of Norfolk. The 3rd Duke was attainted (and his eldest son was beheaded) in 1547 but restored in 1553; his grandson became the 4th Duke. The 4th Duke was beheaded by Elizabeth for plotting to marry Mary, Queen of Scots (as his fourth wife -- he had already buried three heiresses); the 4th Duke's great-great grandson was restored as the 5th Duke by Charles II in 1660.(32)
The second way a peerage can become extinct is indirectly, when the current title-holder dies, and there is no heir who can trace a direct descent from the first peer and is eligible to inherit it according to the terms of the original creation.
So if the King makes you Lord Elorr by letters patent that restrict descent to legitimate male heirs, but you have no such heir who still is alive when you die, then your title dies with you. Or if you pass your title to your only son, who in turn has no sons of his own, then the title becomes extinct when your son dies. It becomes extinct because there is no lawful male heir of your son (the current holder of the title) or of you (the original grantee) to inherit. A surprising number of noble titles have become extinct in exactly this way, within three generations of the original creation.
When a peerage becomes extinct, it reverts to the crown, and the crown can, if it so chooses, bestow the title anew on a member of a different family (either another branch of the original clan, or a totally different and unconnected family). This would be a new creation, requiring new letters patent, and would set up another opportunity for the peerage to either continue in the new line or become extinct again.
Even the peerages bestowed by the monarch upon his or her own children are hereditary.(33) (It is worth noting that although they are born princes, the Queen's sons must be elevated to become dukes.(34))
There are currently two Dukes of the Blood Royal who are first cousins to the Queen, descended from George V. They are Prince George, Duke of Kent and Prince Richard, Duke of Gloucester (George's younger brother has no extraneous titles and is known simply as Prince Michael of Kent).(35)
George III's sons were created as follows:
The title Duke of Gloucester was held by George III's brother William Henry (created before 1762), and was passed on to his son, who died without issue (and was later revived by George V for his son Henry, as noted above). The title Duke of York was also held by another of George III's brothers, Edward Augustus, and the Duke of Cumberland by his brother Henry Frederick, both of whom died without issue.(36)
The Princess Royal is a lifetime title (i.e., not hereditary), bestowed only upon the eldest daughter of the Sovereign, but entirely at the Sovereign's discretion. The Queen created Princess Anne the Princess Royal in 1990.(37)
Prince Philip was born a Prince of Greece and Denmark. However, that is not why he is called "Prince" today. He renounced his royal title when he became a British citizen in 1947 and took his family's British-adopted surname of Mountbatten. Then, "[t]he engagement of Lieutenant Philip Mountbatten to Princess Elizabeth was announced in July 1947 and the marriage took place in Westminster Abbey on 20 November. Shortly before the wedding, the bridegroom was created Duke of Edinburgh, Earl of Merioneth and Baron Greenwich with the style of His Royal Highness and appointed a Knight of the Garter by the King."(38) I am pretty sure that it is his "style" of H.R.H. which allows him to be called "Prince."
The Queen's grandchildren, like all children of peers, take their titles from their fathers. Her grandchildren by her sons are princes and princesses.(39) But her grandchildren by her daughter -- and also the children of her sister, who are the grandchildren of George VI -- are not princes or princesses, but merely whatever titles are derived from the ranks of their fathers, and the fact that their mothers were daughters of monarchs ir irrelevant.
In Princess Margaret's case, the Queen created her husband an earl, thus indirectly allowing her [the Queen's] nieces and nephews the titles and precedence of the children of an earl. But they don't derive any titular benefits by virtue of being a king's grandchildren.
In Princess Anne's case, her children have no titles at all -- both because Anne has refused the titles her mother wished to bestow upon them, and because their father -- otherwise the source of their courtesy titles -- was a plain Mr. They haven't been stripped of or denounced any titles, but the Queen will have to create new titles for them if they are to rise above the level of "Mr." and "Miss." Any hypothetical titles they would have by virtue of birth still derive only from their father's rank, not their mother's, even though she is the daughter of a reigning monarch!
(Surely both Princess Anne's and Princess Margaret's children must take precedence above all others not more closely related to the monarch -- but my 1818 Peerage book's Table of Precedence does not include Sisters of the King, or Children of Sisters of the King, or Granddaughters of the King! Anyone with a definitive answer regarding the precedence of the Queen's nieces, nephews, and grandchildren by her daughter, please write to me!)
There is more about royal titles in the section on dowagers.
On to Life Peerages
Titles of Nobility In Britan
Hereditary Peerages, including Royal Titles
Rights and Privileges of Peers
A Peeress "in her own right"
Entails, Marriage Settlements, and Dower
Correct Forms of Address
The 1st Duke of Marlborough
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