The sitter was the youngest son of William FitzHerbert. He was educated at Eton and St John's College, Cambridge. He spent most of his life abroad in diplomatic roles, the first of which being a minister at Brussels before being dispatched to Paris to negotiate (along with the States General of the United Provinces) a peace between France and Spain. He was also involved in the peace negotiations between the American colonies. In 1783 he was promoted to Envoy Extraordinary to Empress Catherine the Great of Russia and he accompanied her in her tour of the Crimea in 1787. He later returned to Russia and spent his final foreign mission in St Petersburg in 1801. His visit was aimed at agreeing a peace treaty between England and the new Russian Tsar, Alexander I. The terms were agreed and he was rewarded by being promoted to the English peerage as Baron St Helen's in the Isle of Wight and Count of Southampton. Another notable event in his diplomatic career was his involvement in the dispute between Great Britain and Spain over the right of British subjects to trade at Nootka Sound and to carry on the southern whale fishery. In recognition of his involvement he was raised to the Irish peerage as Baron St Helens. The following year, Commander George Vancouver and the officers of HMS Discovery made the Europeans' first official sighting of Mount St Helens which surveying the northern Pacific Ocean coat. Vancouver named the mountain after FitzHerbert. In his retirement he was created Lord of the Bedchamber to King George III, to whom he was very close. FitzHerbert died without issue and his property and his title thus became extinct. His property passed to his nephew, Sir Henry FitzHerbert.
Another version of the present miniature of the same year is at Burghley House (inv. no. MIN0081).