Sir William Slingsby (29 January 1563 – 1634), was an English soldier, who is often erroneously noted as the discoverer of the first spa water well in Harrogate, North Yorkshire. He was the seventh, but third surviving son of Sir Francis Slingsby and Mary de Percy, daughter of Sir Thomas Percy, executed for his part in the Pilgrimage of Grace, and sister of Thomas Percy, 7th Earl of Northumberland, and Henry Percy, 8th Earl of Northumberland. The Percies were descendants of Saer de Quincy, 1st Earl of Winchester. He was born in Scriven, Knaresborough, West Riding. After marrying Elizabeth Broard, daughter of Sir Stephen Broad of Broadshill, Sussex in 1582, the couple took a Grand Tour of Europe, returning in 1594. In 1596, Slingsby discovered that water from the Tewit Well mineral spring a