Daughter of Alexander Erskine (d. 1756), 5th Earl of Kellie, and Janet Pitcairn (1699-1775). Sister of Boswell's close friend in his younger years Andrew Erskine as well as of Anne, Jenny, Archibald and Thomas Alexander. Married to Walter Macfarlane from 1760 until his death in 1767. On September 25th, 1768 she married Alexander Colville, 7th Lord of Culross (1717-1770), who was appointed vice-admiral of the navy in 1769.
Elizabeth was a sister of Boswell's good friend Andrew Erskine, and she eventually became one of his closest female friends. When Boswell visited the family at Kellie on October 30, 1762, he described her as "a woman of noble figure and majestic deportment, uncommon good sense and cleverness" - a few days later he wrote how he felt very passionate about her, during his stay at Kellie. (November 6)
Boswell visited Lady Betty and her family often during their stay in London 1762-63. Although he sometimes grew tired of their Scottish ways, which didn't quite fit into his plans to become a part of London society, Lady Betty and her family did seem to offer Boswell some much needed homely surroundings and humour. Lady Betty arrived with Anne and Andrew Erskine and Jean Dempster on Dec 1, 1762. She and Anne rented a house on Leicester Square (LJ021262), where they stayed until they left London on March 14, 1763.
Boswell gives a rather harsh description of her in his entry for December 2, 1762, due to her marriage with the much older Walter Macfarlane, but on the whole Boswell and Elizabeth stayed good friends for the remainder of their lives, and Boswell often dined with her (and her family) later on, in Edinburgh