She was born to Elizabeth Kerrill and Jeffrey Amherst (1677–1750) of Kent, one of two girls and seven boys. She married John Thomas, rector of Nutgrove, Cheshire and of Welford, Gloucestershire; the couple had no biological children and adopted a son, the child of a brother-in-law. One of her brothers, Jeffery, became Baron Amherst in 1776 and later was made a field-marshal: he was Commander-in-Chief of the British forces when they took Montreal in 1760.
Elizabeth Amherst was an avid fossil collector and maintained an active correspondence on the subject both before and after her marriage. Her poetry, described as "sprightly" (Greer et al. 179), would seem to have circulated mainly in manuscript, though a few poems were printed anonymously in the 1760s. They are mainly known, however, from the Bodleian manuscript, "The Whims of E.A. afterwards Mrs. Thomas."
