Katherine de Rouet was born in about 1350 in Hainult, now in Belgium, the daughter of a Flemish Herald, Sir Payne de Rouet. She was educated at a convent in Romsey, Hampshire and later joined her sister Philippa, who became the wife of Geoffrey Chaucer. at the court of King Edward III.
Katherine married Sir Hugh Swynford of Kettlethorpe and Coleby, Lincolnshire, about 1366. Sir Hugh died in 1371 in Gironde, Bordeaux.
John of Gaunt, the 3rd son of King Edward III was born in Ghent in 1340. He married his first wife, Blanche of Lancaster, his third cousin, in 1359. Blance died of bubonic plague in 1369 at Bolingbroke castle.
He married Infanta Constanza of Castile in 1371 at Roquefort near Bordeaux, assuming the title “King of Spain” in 1372. In 1387 he tried, with the aid of King Joao I of Portugal, to conqueror Castile to make good his claim, but was unsuccessful.
During John of Gaunt’s marriage to Constance he fathered four children by his childrens’ governess, Katherine Swynford. John built a large house for Katherine and their children opposite St Mary’s Guildhall.
Constanza died in 1394.
John of Gaunt married Katherine Swynford in Lincoln Cathedral in 1396. John of Gaunt had many titles and with his marriage to Katherine he gained the title Earl of Lincoln. Following the marriage John and Katherine’s four children were legitimised, taking the surname of Beaufort, but were prevented from inheriting the throne. The children were:
- John Beaufort, 1st Earl of Somerset (1373-1410)
- Henry Beaufort, Cardinal (c. 1374-1447)
- Thomas Beaufort, 1st Duke of Exeter (1377-1426)
- Joan Beaufort, Countess of Westmorland. (1379-1440)
Henry Beaufort was bishop of Lincoln from 1398 to 1405 and was created Cardinal in 1426.
Although John of Gaunt didn’t inherit the English throne all sovereigns of England and Great Britain from Henry IV are his descendants.
John of Gaunt died in 1399, his estates were declared forfeit by King Richard II as John’s son and heir, Henry Bolingbroke, had been exiled. Henry returned to England to depose Richard and reigned as King Henry IV until 1413.
Katherine died on 10th May 1403 and is buried in Lincoln Cathedral.