The Bonham Carter family are descendants of John Bonham-Carter (1788–1838), a British Member of Parliament and barrister, and his wife Joanna Maria Smith. The MP was the son of Sir John Carter (before 20 December 1741 – 18 May, 1808, Mayor of Portsmouth, and son of John Carter, who was a merchant). He assumed the name Bonham by Royal Licence when he inherited the estates of his cousin Thomas Bonham. Joanna Maria Smith was the daughter of William Smith, the abolitionist MP; her sister Frances was the mother of Florence Nightingale, and her brother Benjamin was the father of Barbara Bodichon and Benjamin Leigh Smith. Most of the Bonham-Carters and their circle belonged to Unitarian churches.