She was the only child and sole heiress of Thomas Horner (1688–1741) (later Strangways-Horner), MP, of Mells Manor, Mells, Somerset. Her mother was the heiress Susannah Strangways,[1] one of the two daughters of Thomas Strangways (1643–1713) of Melbury House in Dorset, a major landowner. The other daughter, Elizabeth Strangways (died 1729), married James Hamilton, 5th Duke of Hamilton, as his second wife,[2] but died childless. Susanna Strangways was the co-heiress of her childless brother Thomas Strangways (died 1726) and, after the death of her sister the Duchess of Hamilton in 1729, sole heiress.
On 15 March 1736, at the age of 13, Elizabeth married Stephen Fox, the 31-year-old future earl. A homosexual, he was for many years the lover of John Hervey, 2nd Baron Hervey, whose letters to him have been published. Hervey was angered by the marriage and broke off his relationship with Fox.[3]
He was raised to the peerage in 1741 and was created an earl on 17 June 1756, making his wife a countess. In 1758, the earl took the additional surname and arms of Strangways in compliance with the terms of his wife's inheritance.
Initially, the earl and countess did not live together[4] because of Elizabeth's youth. Several of their children died in infancy.[5] Those who survived to adulthood were:
^ G.E. Cokayne; with Vicary Gibbs, H.A. Doubleday, Geoffrey H. White, Duncan Warrand and Lord Howard de Walden, editors, The Complete Peerage of England, Scotland, Ireland, Great Britain and the United Kingdom, Extant, Extinct or Dormant, new ed., 13 volumes in 14 (1910–1959; reprint in 6 volumes, Gloucester, U.K.: Alan Sutton Publishing, 2000), volume VI, page 269.