up at the English royal court, later found herself in the service of Blanche of Lancaster, the first wife of John of Gaunt. At that time, she was married to Hugh Swynford (or de Swynford), one of the Duke's knights. After the death of the Duchess, Katherine became the lady-in-waiting of her daughters, and also took care of them.

After the death of Hugh Swynford, she became a member of the household of the Duke's new wife, Constance of Castile,