The first Sovereign to reign over England, Scotland, and Ireland simultaneously was James who ruled in Scotland as James VI from the age of 18 months, and in England and Ireland as James I from 1603. He was the first King of England of which Royal House?
James VI and I James VI and I James VI and I (James Charles Stuart; 19 June 1566 – 27 March 1625) was King of Scotland as James VI from 24 July 1567 and King of England and Ireland as James I from the union of the Scottish and English crowns on 24 March 1603 until his death in 1625. The kingdoms of Scotland and England were individual sovereign states, with their own parliaments, judiciaries, and laws, though both were ruled by James in personal union. James was the son of Mary, Queen of Scots, and a great-great-grandson of Henry VII, King of England
Union of England and Scotland Act 1603 Union of England and Scotland Act 1603 The Union of England and Scotland Act 1603 (1 Jac. I c.2), full title "An Act authorizing certain Commissioners of the realm of England", was an Act of Parliament of the Parliament of England enacted during the reign of King James I. It appointed a commission led by the Lord Chancellor, Lord Ellesmere, to meet and negotiate with a commission which would be appointed by the Parliament of Scotland. The aim of the discussions was to look into the possibility of arranging a formal political union between England and Scotland, going beyond the