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
Mary, Queen of Scots in Loch Leven Castle. On 24 July 1567 she was forced to abdicate in favour of her one-year-old son. After an unsuccessful attempt to regain the throne, she fled southwards seeking the protection of her first cousin once removed, Queen Elizabeth I of England. Mary had once claimed Elizabeth's throne as her own, and was considered the legitimate sovereign of England by many English Catholics, including participants in a rebellion known as the Rising of the North. Perceiving her as a threat, Elizabeth had her confined in various castles and manor houses in the interior of England. After eighteen and