^For example, the present (19th) duke was known as The Honourable John Seymour from his birth on 30 December 1952 until the death of his grandfather (the 17th duke) on 26 April 1954.
^For example, The Honourable Charles Henry Gordon-Lennox (15 August 1895 – 5 September 1895) was born and died in the lifetimes of his great-grandfather the 6th duke, his grandfather (then known as Earl of March) and his father (then known as Lord Settrington)
^For example, the 9th duke was known as The Honourable John Fitzroy from his birth on 1 August 1914 until the death of his father (William FitzRoy, Viscount Ipswich) on 23 April 1918.
^For example, the 14th duke was known as The Honourable Henry 'Robin' Russell from his birth on 21 January 1940 until the death of his great-grandfather the 11th duke on 27 August 1940.
^ abThe eldest son of the current Duke opts to continue using the courtesy title afforded to the grandson of Dukes, which he used in his grandfather's lifetime, in lieu of the title traditionally used by the heir apparent.
^ abNot currently in use, as the appropriate heir bears the title of prince.
^For example, the current (7th) was known as The Honourable Robert Gascoyne-Cecil from the death of his great-grandfather (the 4th marquess) on 4 April 1947 until the death of his grandfather (the 5th marquess) on 23 February 1972.
^ abcdefThis peer in fact bears no subsidiary title with a territorial designation different from his substantive title; the family's surname is substituted for the courtesy title instead.
^Prior to the then future 3rd Earl Mountbatten of Burma succeeding to the title of Baron Brabourne, the heir to the Earldom used the courtesy title Lord Romsey.