His eldest son is therefore styled "Earl of Arundel" (without the definite article "The" which indicates a substantive title). Lord Arundel's eldest son (should he have one during his father's lifetime) would be styled "Lord Maltravers". However, only the Duke of Norfolk is actually a peer; his son Lord Arundel and his hypothetical grandson Lord Maltravers are not. Courtesy titles are only used by the peer's eldest living son, and the eldest son's eldest living son, 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. However, Scottish practice allows the style "Master/Mistress of X" to an heir presumptive as well as to an heir apparent; for example, the brother of the present Marquess of Tweeddale has the title "Master of Tweeddale". Wives are entitled to use the feminine form of their husbands' courtesy titles. Thus, the wife of an Earl of Arundel would be styled "Countess of Arundel" (again, without the article). Holders of courtesy titles do not, at the Court of St James's, have their title preceded by the definite article "The": e.g., 'Earl of Arundel' rather than 'the Earl of Arundel'. The actual courtesy title which is used is a matter of family tradition. For instance, the eldest son of The Duke of Buccleuch and Queensberry is styled "Earl of Dalkeith", even though the duke is also The Marquess of Dumfriesshire, a title which outranks the earldom. Similarly, the eldest son of The Marquess of Londonderry is styled "Viscount Castlereagh", even though the marquess is also The Earl Vane. Titles with the same name as a peer's main title are not used as courtesy titles. For instance, The Duke of Westminster is also The Marquess of Westminster and The Earl Grosvenor (amongst other titles). The duke's heir apparent (when there is one) is not styled "Marquess of Westminster", which would cause confusion between the son and the father, and so is styled "Earl Grosvenor" instead.