Sir William Hamilton, KB, PC, FRS, FRSE (13 December 1730 – 6 April 1803) was a British diplomat, politician, antiquarian and vulcanologist who served as the Envoy Extraordinary to the Kingdom of Naples from 1764 to 1800.

After sitting in the House of Commons of Great Britain from 1761 to 1764, he began working as a diplomat, succeeding Sir James Gray as the British ambassador to the Kingdom of Naples.

While in Italy, Hamilton became involved in studying local volcanoes and collecting antiquities, becoming a fellow of the Royal Society and being given the Copley Medal.

[3] His mother was a favourite, and possibly a mistress, of the Prince of Wales and William grew up with his son George III, who would call him his "foster brother".

When he heard that the ambassador to the court of Naples, Sir James Gray, was likely to be promoted to Madrid, Hamilton expressed an interest in the position, and was duly appointed in 1764.

Hamilton began collecting Greek vases and other antiquities as soon as he arrived in Naples, obtaining them from dealers or other collectors, or even opening tombs himself.

Soon after Hamilton arrived in Naples, Mount Vesuvius began to show signs of activity and in the summer of 1766 he sent an account of an eruption, together with drawings and samples of salts and sulphurs, to the Royal Society in London.

Hamilton subsequently hired a priest, Padre Antonio Piaggio, who lived near the western slopes of Vesuvius to keep a regular diary of notes and sketches of the volcano.

[24] The Hamiltons gave musical entertainments in which they played (William the violin, and Catherine the harpsichord or pianoforte) with some of their servants or professional musicians.

[29] Catherine Hamilton died in August 1782; her body was returned to Britain for burial in the Barlow vault at the old Slebech parish church.

Hamilton wrote to his niece Mary: "I must for ever feel the loss of the most amiable the most gentle and virtuous companion that ever man was blessed with".

In 1783 he published some of those findings in a slim volume, The Worship of Priapus: An account of the fete of St. Cosmo and Damiano celebrated at Isernia in 1780...

This time he visited his estates in Wales and went on a trip to Scotland with his nephew Charles Greville, who was a younger son of the Earl of Warwick and Hamilton's sister Elizabeth.

[33] Meanwhile, Greville, who wanted to search for a wealthy wife, was hatching a plan to persuade his uncle to take Emma off his hands.

The ceremony was a quiet one in St Marylebone Parish Church, taking place on 6 September 1791, two days before the couple's return to Naples.

Emma signed the register as Amy Lyons; the witnesses were Hamilton's cousin the Marquess of Abercorn and Louis Dutens, who had been chaplain at Turin.

But when France declared war on Britain in 1793 events in Naples became more turbulent, and Hamilton's role became more important, just as his health was declining.

At the end of the year the King and Queen abandoned Naples as the French Army advanced and fled to Palermo in Sicily.

Hamilton, together with the king and queen, and Nelson, remained in Palermo, except for a visit to the Bay of Naples in Foudroyant when he briefly went ashore.

Hamilton would live in retirement for another two and a half years, at Merton with Emma, Nelson, and Mrs Cadogan, and in a house he leased in Piccadilly.

He spent his time fishing on the River Thames, visiting his estates in Wales, selling paintings and vases, trying to get money owed to him by the government for his expenses in Naples, and attending his clubs, especially the Royal Society and the Dilettanti.