http://file3.status.net/i/identica/jim-20120913T171953-swa8frn.html

"Gaunt's nephew Richard III legitimised Gaunt's children by Katherine Swynford by Letters Patent in 1397. In 1407, Henry IV, who was Gaunt's son by his first wife, issued new Letters Patent confirming the legitimacy of his half-siblings, but also declaring them ineligible for the throne. Henry IV's action was of doubtful legality, as the Beauforts were previously legitimised by an Act of Parliament, but it further weakened Henry's claim." ~from #wikipedia