The very fact that Henry Tudor became King of England at all is somewhat of a miracle. His claim to the English throne was tenuous at best. His father was Edmund Tudor, a Welshman of Welsh royal lineage, but that was not too important as far as his claim to the English throne went. What was important though was his heritage through his mother, Margaret Beaufort, a descendant of Edward III. This descent from King Edward was through his third son, John of Gaunt. John’s third wife, Katherine Swynford had borne him several children as his mistress before he married her. The children born before the marriage were later legitmized, but barred from the succession. Margaret Beaufort was descended from one of the children born before the marriage of John and Katherine.