He was the son of Sir Stephen Fox and his second wife Christiana Hope. Henry Fox, 1st Baron Holland, was his younger brother and the Radical politician Charles James Fox his nephew. He served as MP for Shaftesbury from 1726, until 1741, when he was raised to the peerage as Lord Ilchester, of Ilchester in the County of Somerset, Baron of Woodford Strangways in the County of Dorset. Six years later he was created Lord Ilchester and Stavordale, Baron of Redlynch, in the County of Somerset, and in 1756 he was even further honoured when he was made Earl of Ilchester. The peerages were created, in default of male issue of his own, with remainder to his younger brother Henry. In 1763 he was admitted to the Privy Council.
Stephen Fox was the lover of Lord Hervey from 1726 to 1736. There exist many passionate letters between the two. Hervey initially favored Stephen's brother Henry, but when charmingly rebuffed paid infatuated court to Stephen. His relationship with Lord Hervey ended only when a marriage was arranged with thirteen-year-old Elizabeth Horner, daughter of Thomas Strangways Horner and Susanna Strangways, in 1735. In 1758, Lord Ilchester assumed the additional surname of Strangways. He died in September 1776, aged 72, and was succeeded by his son Thomas Fox-Strangways.
- http://rictornorton.co.uk/hervey1.htm "The Gay Love Letters of John, Lord Hervey to Stephen Fox"; excerpts from My Dear Boy: Gay Love Letters through the Centuries (1998), edited by Rictor Norton