Peter Thellusson, 1st Baron Rendlesham

Peter Isaac Thellusson, 1st Baron Rendlesham (13 October 1761 – 16 September 1808), was a British merchant, banker and politician.

His grandfather, Issac de Thellusson, became Genevan ambassador at Paris to the Court of Louis XV,[2] where his uncle, George, founded a banking house.

At the general election, he was returned for Castle Rising as "a paying guest of the Prince of Wales's friend Lord Cholmondeley" from 1802 to 1806 and for Bossiney from 1807 to 1808.

In July 1805 he asked Pitt to "expedite an earlier promise to recommend him for an Irish peerage by invoking the power vested in the crown" by the Acts of Union 1800 to create one new peer when three Irish titles had become extinct, as they had, so Thellusson claimed, with the deaths of the Earl of Mountrath, Viscount Bateman and Lord Ross in 1802.

While Thellusson was mistaken, because Mountrath's barony passed by special remainder to Charles Henry Coote, upon Baron Holmes's death in 1804, the required three were obtained.