Katherine was “Gaunt's long-term mistress and third wife. The Beaufort children, three sons and a daughter, were legitimised by royal and papal decrees after John and Katherine married in 1396; a later proviso that they were specifically barred from inheriting the throne, the phrase excepta regali dignitate (except royal status), was inserted with dubious authority by their half-brother Henry IV.”703

Katherine became attached to the household of John of Gaunt as governess to his Blanche’s daughters Philippa and Elizabeth.725