Sir Thomas Dereham, 4th Baronet

Sir Thomas Dereham, 4th Baronet
Medal of Thomas Dereham aged 36 by Massimiliano Soldani Benzi
Born	1678 West Dereham Abbey, Norfolk, England
Died	16 January 1738 (1738-01-17) (aged 59) Rome, Italy
Nationality	English
Known for	Informal Jacobite ambassador to Rome

Sir Thomas Dereham, 4th Baronet (or Derham) (ca. 1678-1739) was an English baronet who spent most of his life in Italy, where he acted as an informal representative for the Old Pretender, known as James III to his supporters.

Sir Thomas Dereham was born in West Dereham Abbey, Norfolk. He was the grandchild of Sir Thomas Dereham, 1st Baronet, who was made a baronet by Charles II of England on 8 June 1661. His father was Thomas's second son, Sir Richard Dereham, and his mother was Frances Villiers. Dereham was an Anglo-Catholic. He was given into the care of his cousin, also called Thomas Dereham, envoy to the court of Tuscany. He later inherited the property of his cousin. He was educated in Florence at the court of Cosimo III de' Medici, Grand Duke of Tuscany.

Dereham moved to Rome where he acted on behalf of the Old Pretender, James Francis Edward Stuart, known as James III to his supporters, in dealings with Pope Clement XII and the local English community who supported the Stuart cause. For many years Dereham was a close friend of Clement XII and his nephew, Cardinal Andrea Corsini. In March 1733 Baron Philipp von Stosch, a resident of Rome who was paid to report on events to the English government, wrote that, "Sir Thomas Dereham is playing the part of the Pope's favorite, and is extremely influential with Cardinal Corsini." Stosch said he acted as a Minister and considered that he was "protector of the British nation."

Dereham became a Fellow of the Royal Society in 1720. He sent regular reports on Italian science from Italy to the Royal Society. In 1722 he entered into a correspondence with James Jurin, secretary of the Royal Society, and with Sir Isaac Newton, President of the Society, in which he offered to act as an intermediary in "opening a Philosophical Communication between two nations, among both which have been, & are so many generous spirits, as you say, united in the same noble design, for the common benefit, & information of mankind." He reported on the development of the Academy of the Institute of Sciences and the Arts of Bologna, recently founded by Luigi Ferdinando Marsigli, and of the society being developed in Milan, promoted by Celia Grillo Borromeo. Dereham undertook a translation into Italian of the Philosophical Transactions of the Royal Society, whose first volume appeared in 1729.