Daughter of Francis Greville (1719-1773), 1st Earl of Warwick and 1st Earl Brooke, and Elizabeth Hamilton (d. 1800). Married (1762) to John Stewart. She may have had two sons, both of whom died in infancy.
Boswell met with her and her husband at the Earl of Galloway's on September 25, 1762, and again in London on December 19 of that year. On the first occasion, he described her as "very little and very young, but [with] a sweetness and composure that is very pleasing. She has been well educated and has a turn for all little amusements that serve to fill up vacant time, such as painting flowers and cutting paper, both which she excels in."