Henry Stuart, Lord Darnley not together in early 1545 and a letter of March 1566, from Mary Queen of Scots, indicates Darnley was then nineteen years old. Therefore the date 1546 would seem probable. A descendant of both James II of Scotland and Henry VII of England, Henry Stuart, Lord Darnley, was heir to two royal houses, the House of Stuart and the House of Tudor, thus he had claim to both the Scottish and English thrones, a claim that may have cost him his life. In 1545, his father, Matthew Stewart, 4th Earl of Lennox was found guilty of treason in Scotland for
James VI and I Stuart, Lord Darnley. Both Mary and Darnley were great-grandchildren of Henry VII of England through Margaret Tudor, the older sister of Henry VIII. Mary's rule over Scotland was insecure, and she and her husband, being Roman Catholics, faced a rebellion by Protestant noblemen. During Mary's and Darnley's difficult marriage, Darnley secretly allied himself with the rebels and conspired in the murder of the Queen's private secretary, David Rizzio, just three months before James's birth. James was born on 19 June 1566 at Edinburgh Castle, and as the eldest son and heir apparent of the monarch automatically became Duke of Rothesay