‘Leicester house’, those politicians associated with the Prince of Wales' court in Leicester Square Fields, played an important part in the development of the concept of ‘Opposition’ during the eighteenth century, and particularly between 1717 and 1760. There were several periods when this faction was particularly active, and these activities have acquired peculiar importance for many historians in view of the supposed intentions of George III of putting into effect precepts urged either at his own court as Prince of Wales or at that of his father, Frederick. As a result, considerable attention has been paid to the activities of Leicester House, and particularly to Frederick and his colleagues. Although Frederick was active, politically, between 1737 and 1751, it was after 1746 that he was virtually head of the Opposition, and it is in this period that he becomes most interesting, perhaps because it is for these years that there exists a body of documents illustrating his activities in such detail that it is possible to ascertain the nature of his plans. None of Frederick's own papers survive, and the documents in the Royal Archives at Windsor are derived from the records of his earlier associates. His principal associate after 1749 was John Perceval, second Earl of Egmont, whose father's diaries were published by the Historical Manuscripts Commission some forty years ago. Egmont was a Lord of the Bedchamber to the Prince and was the last in a series of favourites intended as future Prime Ministers, so that the papers drawn up in consultation between the two undoubtedly represent the intentions and plans of the Prince in these years and especially in the spring of 1750, to which period many can be dated from internal evidence.