Henry Frederick Stuart, born at Stirling Castle on 19 February 1594, was the eldest child of King James VI of Scotland. Following his father’s accession to the crowns of England and Ireland upon the death of Elizabeth I in 1603, he became the heir to the thrones of three kingdoms. Created Duke of Cornwall that year and installed as Prince of Wales in 1610, Henry was to die on 6 November 1612, at the age of eighteen, of what was probably typhoid fever. Quite different from his father – he was charismatic, brave, cultured and deeply committed to reformed causes – Henry had already gained a certain celebrity status in Europe and was coming to be regarded by many as England’s great hope for the future by the time of his death. He was replaced as Prince of Wales by his younger brother Charles, who succeeded as king in 1625, and we all know how that turned out: Charles provoked all three of his kingdoms to rebel against him and, after suffering defeat in two bloody civil wars, was tried and executed for treason in January 1649. Henry’s story is thus one of the great what ifs of English history: how might things have been different if James VI and I had been succeeded by Henry IX and not Charles I?