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 as a Scheduled Monument and is open to the public. William the Conqueror granted the area to Judith of Lens, wife of Waltheof, Earl of Northumbria. Their eldest daughter, Maud, inherited the lordship of Fotheringhay. Around 1090, she married Simon de Senlis who was made Earl of Huntingdon. Probably in around 1100, he founded Fotheringhay Castle, a Norman motte on the north side of the River Nene. Simon was dead by 1113 when King Henry I of England arranged for Maud to marry Prince David of Scotland. Through this marriage, David who later became King of Scotland, acquired Fotheringhay Castle