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 before her execution. She spent her final night praying in the castle's small chapel. She was beheaded on a scaffold in the castle's great hall on 8 February 1587. Despite the castle's size and importance, it was allowed to fall into disrepair during the latter part of the Elizabethan period. By 1635, less than 50 years after Mary, Queen of Scots' execution, it was reported to be in a ruinous state and was completely demolished soon afterwards. The castle is a Scheduled Monument, a "nationally important" historic building and archaeological site which has been given protection against unauthorised change. Today