From Hugh Smithson to the Duke of Northumberland
His father was Sir Hugh Smithson, baronet (1714–1786), which made the little boy heir to that hereditary knighthood. Sir Hugh had served in House of Commons and filled several royal offices before inheriting that title from his grandfather.
The baby’s mother had been born in 1716 as Elizabeth Seymour, only daughter of Lord Algernon Seymour, son and heir of the Duke of Somerset. Lord Algernon also served in Parliament and as an army officer and colonial governor. In 1722 a clerical error had made him Baron Percy, granting him a title from his mother.
In October 1749 the Crown made Sir Hugh Smithson the first Baron Warkworth. The family barely had time to adjust to that before more significant changes happened. First, in January 1750, young Hugh got a baby brother named Algernon, after their maternal grandfather.
In February, that grandfather died. He had recently acquired more noble titles—Duke of Somerset, Earl of Hertford, Earl of Northumberland, Earl of Egremont, Baron Cockermouth (really), and so on. However, he had no male heirs. Therefore, by special arrangements his titles were doled out to his nephews, cousin, and son-in-law.
Baron Warkworth became Earl of Northumberland. In exchange, he petitioned Parliament to change his family’s surname to Percy; that law was passed in April.
Seven-year-old Hugh Smithson thus became Hugh Percy, but because he was now the oldest son of an earl, as a courtesy he was addressed by his father’s lesser title as Lord Warkworth.
Under that title, Hugh joined the British army. Within a year, still aged only seventeen, he was captain of a regiment. He saw action at the battles of Bergen and Minden. After a short time at Cambridge University, in 1763 Lord Warkworth was elected to the House of Commons as a member for Westminster. The next year, he married a daughter of the Earl of Bute, the former prime minister. By then he was a colonel.
In 1766 the colonel’s father, the Earl of Northumberland, was granted higher titles: Duke of Northumberland and Earl Percy. The latter rank became the courtesy title for his son Hugh.
That’s why the army colonel who served as Gen. Thomas Gage’s second-in-command at the start of the Revolutionary War was referred to as Hugh, Earl Percy. When his mother died in 1776, he inherited the barony of Percy in his own right, but fortunately that didn’t require people to call him by a new name.
In 1786 Lord Percy’s father died, and he became the second Duke of Northumberland. By special arrangement, his younger brother Algernon (then sitting in the House of Commons) inherited a new title, Baron Lovaine; four years later he was made the Earl of Beverley. (They also had an illegitimate half-brother named Jacques-Louis Macie and then James Smithson, who endowed the Smithsonian Institution.)