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 took her into protective custody at Carlisle Castle. Mary apparently expected Elizabeth to help her regain her throne. Elizabeth was cautious, ordering an inquiry into the conduct of the confederate lords and the question of whether Mary was guilty of Darnley's murder. In mid-July 1568, English authorities moved Mary to Bolton Castle, because it was further from the Scottish border but not too close to London. A commission of inquiry, or conference as it was known, was held in York and later Westminster between October 1568 and January 1569. In Scotland, her supporters fought a civil war against Regent Moray