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 a half years in custody, Mary was found guilty of plotting to assassinate Elizabeth in 1586. She was beheaded the following year at Fotheringhay Castle. Mary was born on 8 December 1542 at Linlithgow Palace, Scotland, to King James V and his French second wife, Mary of Guise. She was said to have been born prematurely and was the only legitimate child of James to survive him. She was the great-niece of King Henry VIII of England, as her paternal grandmother, Margaret Tudor, was Henry VIII's sister. On 14 December, six days after her birth, she became Queen of Scotland