David Laing (1793–1878): Antiquarian and librarian. Born in Edinburgh, he was the son of the publisher and antiquarian bookseller William Laing (1764–1832; DNB) and his wife Helen (1767–1837). The elder Laing had lent books to help Southey with his edition of Le Morte d'Arthur (1817) and Southey visited his shop on his trips to Edinburgh in 1806 and 1819. David Laing entered his father’s business, becoming a partner in 1821. As well as being highly regarded for his professional knowledge, Laing also assembled his own extensive collection of books and manuscripts.

Susanna Maria Koster (née Carrett; 1760–1842): Wife of John Theodore Koster, whom she married in Lisbon in 1778. The couple had twelve children, many of whom died young.

John Theodore Koster (1750–1828): English sugar merchant, whom Southey met in Portugal during his visit of 1800–1801 and again in Liverpool in 1804. Koster lodged in Keswick in 1815–1816 after suffering heavy financial losses and later relocated to France, where he died at Bordeaux. Koster’s home in Lisbon was a meeting place for those interested in the arts and sciences and he was a man of wide interests, a member of the Portuguese Royal Academy of Sciences and a writer on economic matters, including A Statement of the Trade in Gold Bullion (1811).

Henry Koster (1793–1820): Son of the Lisbon merchant, John Theodore Koster. At the age of only sixteen his father sent him to Brazil, both for his health and to set up as a sugar planter. Koster travelled extensively in Pernambuco and returned to England only briefly in 1811 and again in 1815. On the latter occasion, his visit to Southey in Keswick turned into a prolonged stay after Koster was injured in a coach accident.

William Knox (1789–1825): Born in Roxburghshire, Knox was the son of a farmer. He attended Musselburgh grammar school and between 1812–1817 farmed at Wrae, near Langholm, Dumfriesshire. He returned to live with his parents after his farm failed. The family settled in Edinburgh in 1820 and Knox became a writer, supported by John Wilson, who often gave him money. Knox contributed to the Literary Gazette and other journals and published three collections of his own poetry: The Lonely Hearth (1818); The Songs of Israel (1824); and The Harp of Zion (1825).

Herbert Knowles (1798–1817): A member of a family of Nonconformist cloth merchants and manufacturers from Gomersal, near Leeds, Herbert was orphaned in 1805. His relatives eventually recognized his academic talents and he was sent to Richmond Grammar School. Knowles was concerned that he did not have the funds to enter Cambridge University (and possibly that his family would not be prepared to support his ambition to study there).

William Knighton (1776–1836): Courtier and physician. He became a friend of Henry Herbert Southey while the two men were studying medicine at the University of Edinburgh, and set up a London practice in 1806. He was appointed physician to the Prince of Wales (the future George IV) in 1810 and gradually assumed the role of sorting out the Prince’s tangled finances. In 1822 he became Keeper of the Privy Purse and, effectively, George IV’s private secretary. Knighton furthered Henry Herbert’s career, ensuring he succeeded him as physician to George IV in 1823.

John King [Nicholas Johann Koenig] (1766–1846): Bristol-based surgeon, painter and linguist, originally from Berne, Switzerland. He came to England in the 1790s and studied medicine under John Abernethy (1764–1831; DNB) at St Bartholomew’s Hospital, before settling at Clifton in Bristol. He married Emmeline Edgeworth, a sister of the novelist Maria (1768–1849; DNB). Southey came to know King well when he succeeded Davy in his role at the Pneumatic Institution in 1801.

Emmeline King (1770–1847): Younger sister of Maria Edgeworth (1768–1849; DNB). She married John King in 1802 and the couple had two daughters.

John Kidd (1775–1851): Doctor and author of medical treatises. Educated at Westminster School and Christ Church, Oxford (matric. 1793, BA 1797). A friend of Southey’s during his time at Oxford, and possibly a school friend as well.