1678–1739), FRS, 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, the son and heir of Sir Richard Dereham, 3rd Baronet, by his wife Frances Villiers[2] (alias Wright, Howard, Danvers), a daughter of Robert Danvers, Viscount Purbeck (1624-1674) (alias Wright, Howard, Villiers) the illegitimate son of Frances Coke (probably by Sir Robert Howard of Clun Castle, Shropshire), the estranged wife of John Villiers, 1st Viscount Purbeck.

The illegitimate child of a notorious liaison, Danvers had at least four different names, changed his religion four times, and sided according to circumstances with Royalists, Parliamentarians, the restored monarchy, and its opponents.

[4] He was given into the care of his cousin, Sir Thomas Dereham, Knight (d.1697) envoy to Cosimo III de' Medici, Grand Duke of Tuscany.

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 favourite, and is extremely influential with Cardinal Corsini.