Although Henry VII won the Battle of Bosworth, it didn't mean he had the support of the country
Henry's claim came largely through his mother, Margaret Beaufort, a descendant of Edward III through the marriage of his third son, John of Gaunt to Catherine Sywnford
However, the children of the marriage had been born when Catherine was John's mistress and had been legitimised later by parliament during the reign of Richard II
Henry also had some royal blood as his father's mother was a French princess who had been married to Henry V, before marrying Owen Tudor, Henry's grandfather
Henry was the Lancastrian claimant to the throne yet his claim was weak and was likely to be challenged by Yorkist claimants