Baron Leconfield, of Leconfield in the East Riding of the County of York, is a title in the Peerage of the United Kingdom. It was created in 1859 for Col. George Wyndham (1787-1869). He was the eldest illegitimate son and adopted heir of George Wyndham, 3rd Earl of Egremont (1751-1837) (see Earl of Egremont for earlier history of the family), from whom he inherited Petworth House in Sussex, Egremont Castle and Cockermouth Castle in Cumbria and Leconfield Castle in Yorkshire, all formerly lands of Josceline Percy, 11th Earl of Northumberland (1644-1670), inherited by Charles Seymour, 6th Duke of Somerset (1662-1748) on his marriage to the Percy heiress Elizabeth Percy (1667-1722) and inherited as one of the co-heirs of his son Algernon Seymour, 7th Duke of Somerset, 1st Earl of Egremont (16