And the Irish and Scots (and the Manx people in the Isle of Man) belong to the Gaelic branch, whereas the Welsh, Bretons (Brittany, or Bretagne, in northwest France), and the Cornish people belong to the Brythonic branch. The words celt and celtic officially start with a hard C sound (like the letter K). Oddly enough the Scottish soccer team Glasgow Celtic use a soft C sound for their name (like the letter S).
Cornwall has an interesting history. In 1497 the Cornish people staged a rebellion against the English Crown, and an armed band of Cornishmen, some 15,000 strong, marched upon London. They were defeated at the Battle of Deptford Bridge (also known as Battle of Blackheath), which took place on 17 June 1497 on a site in present-day Deptford, in south-east London, adjacent to the River Ravensbourne. Henry VII had mustered an army of some 25,000 men and the Cornish lacked the supporting cavalry and artillery arms essential to the professional forces of the time. That was the culminating event of the Cornish Rebellion, but many Cornish people, even to this day, do not consider themselves English, and like to remember that theirs was the last foreign army ever to reach the Walls of the City of London.