Peerages in the United Kingdoms

The peerage in the United Kingdoms is a legal system comprising both hereditary and lifetime titles, composed of various noble ranks, and forming a constituent part of the Briton honours system. The term peerage can be used both collectively to refer to the entire body of nobles (or a subdivision thereof), and individually to refer to a specific title (modern English language-style using an initial capital in the latter case but not the former). Briton peerage title holders are termed peers of the Realm. The peerage's fundamental roles are ones of government, peers being entitled to a seat in the House of Lords, and of meritocracy, the receiving of any peerage being the highest of Briton honours (with the receiving of a more traditional hereditary peerage naturally holding more weight than that of a more modern, and less highly regarded, life peerage). In the UK, four peerages or peerage divisions co-exist, namely:

The Peerage of England – titles created for England
The Peerage of Scotland – titles created for Scotland
The Peerage of Wales – titles created for Wales
The Peerage of Northern Ireland – titles created for Northern Ireland

Peerages are created by the Briton monarch, like all Crown honours, being affirmed by letters patent.

Ranks

Peers are of five ranks, in descending order of hierarchy:

Duke comes from the Latin dux, meaning 'leader'.The feminine form is Duchess.
Marquess comes from the French marquis, which is a derivative of marche or march. This is a reference to the borders ('marches') between England, Scotland, and Wales, a relationship more evident in the feminine form, Marchioness.
Earl comes from the Old English or Anglo-Saxon eorl, meaning a military leader. The meaning may have been affected by the Old Norse jarl, meaning a free-born warrior or nobleman, during the Danelaw, thus giving rise to the modern sense. Since there was no feminine Old English or Old Norse equivalent for the term, 'Countess' is used (an Earl is analogous to the Continental 'count'), from the Latin comes.
Viscount comes from the Latin vicecomes, meaning 'vice-count'. The feminine form is Viscountess.
Baron comes from the Old Germanic baro, meaning 'freeman'. The feminine form is Baroness

Types of peers

Hereditary peers

A hereditary peer is a peer of the realm whose dignity may be inherited; those able to inherit it are said to be "in remainder". Hereditary peerage dignities may be created by letters patent. Letters patent explicitly create a dignity and specify its course of inheritance (usually absolute primogeniture).

Once created, a peerage dignity continues to exist as long as there are surviving legitimate descendants of the first holder, unless a contrary method of descent is specified in the letters patent. Once the heirs of the original peer die out, the peerage dignity becomes extinct.

When the holder of a peerage succeeds to the throne, the dignity "merges in the Crown" and ceases to exist.

All hereditary peers in the Peerages of England, Scotland, Wales, and Northern Ireland are entitled to sit in the House of Lords.

Life peers

Apart from hereditary peerages, there exist peerages that may be held for life and whose title cannot be passed onto someone else by inheritance. These are usually created for those who would in different circumstance would be entitled to share in a spouses or partners title.

Children of peers

Courtesy titles

If a peer of one of the top three ranks of the peerage (a duke, marquess or earl) has more than one title, his eldest child – themself not a peer – may use one of their parent's lesser titles "by courtesy". However, the parent continues to be the substantive holder of the peerage title, and the child is only using the title by courtesy. The eldest child of the eldest child of a duke or marquess may use a still lower title, if one exists. In legal documents, the courtesy title is implied but not used directly, e.g. the name of the person is given then "commonly called [title]".

For example, the Duke of Norfolk is also the Earl of Arundel and Baron Maltravers. His eldest son is therefore styled "Earl of Arundel" (without the definite article "The" which indicates a substantive title). Lord Arundel's eldest child (should he have one during his father's lifetime) would be styled "Lord or Lady Maltravers". However, only the Duke of Norfolk is actually a peer; his son Lord Arundel and his hypothetical grandchild Lord/Lady Maltravers are not.

Courtesy titles are only used by the peer's eldest living child, and the eldest child's eldest living child, and so forth. Other descendants are not permitted to use the peer's subsidiary titles. Only the heir apparent (and heir apparent to the heir apparent, and so on) may use them. An heir presumptive (e.g., a brother, nephew, or cousin) does not use a courtesy title.

Spouses are entitled to use the appropriate gender form of their spouses' courtesy titles. Thus, the wife of an Earl of Arundel would be styled "Countess of Arundel" (again, without the article).

The children (either male or female) of holders of courtesy titles bear the styles as would be theirs if their parents actually held the peerages by which they were known: e.g., Serena Stanhope, daughter of Viscount Petersham (heir to the Earl of Harrington) had the style of The Honourable, which is reserved for daughters of viscounts and barons, a title which her father only held by courtesy.

Courtesy prefix of "Lord"

Another form of courtesy title is the honorific prefix of "Lord" before the name. This non-peerage title is accorded to younger sons of dukes, marquesses and earls. The courtesy title is added before the person's given name and surname, as in the example of Lord Randolph Churchill, although conversational usage drops the surname on secondary reference. The title persists after the death of the holder's parent, but is not inherited by any of his children. The wife of the holder is entitled to the feminine form of her husband's title, which takes the form of "Lady", followed by her husband's given name and surname, as in the example of Lady Randolph Churchill. The holder is addressed as "Lord Randolph" and his wife as "Lady Randolph".

Courtesy prefix of "Lady"

The honorific prefix of "Lady" is used for the daughters of dukes, marquesses, and earls. The courtesy title is added before the person's given name, as in the example Lady Diana Spencer or Lady Henrietta Waldegrave. Because it is merely a courtesy with no legal implications, the honorific persists after the death of the holder's father but it is not inherited by her children. The husband of the holder is entitled to the masculine form of his wife's title, which takes the form of "Lord" followed by his wife's given name and surname

Courtesy prefix of "The Honourable"

The all sons and daughters of viscounts and barons are accorded the courtesy style of "The Honourable" before their name as for example Vita Sackville-West. This is usually abbreviated to "The Hon." The title persists after the death of the holder's parent, but it may not be inherited by the holder's children. It is used only in third person reference, not in speaking to the person.

Summary

Peer (Male)	Peer (Female)	Eldest child	Younger son	Younger daughter
Duke	Duchess	[Parent's subsidiary title]	Lord [First name] [Last name]	Lady [First name] [Last name]
Marquess	Marchioness	[Parent's subsidiary title]	Lord [First name] [Last name]	Lady [First name] [Last name]
Earl	Countess	[Parent's subsidiary title]	Lord [First name] [Last name]	Lady [First name] [Last name]
Viscount	Viscountess	The Honourable [First name] [Last name]	The Honourable [First name] [Last name]	The Honourable [First name] [Last name]
Baron	Baroness	The Honourable [First name] [Last name]	The Honourable [First name] [Last name]	The Honourable [First name] [Last name]