Son of James and Frances Erskine. Married (1770) to Frances Floyer. Nicknamed the Horse by Boswell and William Temple. He became 7th Earl of Mar in 1824 when that title was restored to the family, after having been lost by his father's uncle John Erskine, 6th Earl of Mar, due to the latters role in the Jacobite Rebellion in 1716.1
- 1John, 6th Earl of Mar, was one of the leaders of the Jacobite rebellion in 1715-6, and he proclaimed James Edward Stuart (the Old Pretender) king of Great Britain on September 6, 1715. When the rebellion collapsed in 1716 he fled with Charles Edward to France and Rome, before he lost favour at the pretender's court. He died in Aachen, Germany, in May 1732.
Boswell and John Francis Erskine were classmates in John Stevenson's class in logic and Metaphysics at Edinburgh University in 1756-57. They may have met occasionally afterwards, and we know that Boswell visited Erskine's parents during his 1762-63 stay in London. On October 15, 1774, Boswell visited Erskine at his house in Alloa.