William FitzWilliam (Lord Deputy) William FitzWilliam (Lord Deputy) Sir William FitzWilliam (1526–1599) was an English Lord Justice of Ireland and afterwards Lord Deputy of Ireland. In 1587, as Governor of Fotheringhay Castle, he supervised the execution of the death sentence on Mary, Queen of Scots. He was the Member of Parliament for Peterborough and represented County Carlow in the Irish House of Commons. He lived at Gainspark, Essex, and Milton Hall. FitzWilliam was born at Milton Hall, Northamptonshire, the eldest son of Sir William (d. 1576) and grandson of William Fitzwilliam, Sheriff of London, who had been treasurer and chamberlain to Cardinal Wolsey and
Fotheringhay Castle de Forz, 3rd Earl of Albemarle, in his rebellion against King Henry III. Forz abandoned the castle and Henry III took it under his control; Fotheringhay remained in royal hands until the reign of Edward II. It was a favoured residence of the Dukes of York, and King Richard III was born here in 1452. It was also the final place of imprisonment of Mary, Queen of Scots, who was tried and executed in the castle in 1587. In the 1630s the castle was dismantled and most of the masonry removed, leaving only the earthworks. The castle site is protected