On 23 Dec 1392 Isabella of Castile Duchess York (age 37) died. She the wife of Edmund of Langley 1st Duke York (age 51). Isabella had travelled to England with her sister Constance of Castile Duchess of Lancaster (age 38) who had married Edmund's elder brother John of Gaunt 1st Duke Lancaster (age 52). Isabella and Edmund's marriage was not, apparently, a happy one. She is known to have had an affair with John Holland 1st Duke Exeter (age 40) who may have been the father of Richard of Conisbrough 1st Earl Cambridge (age 7) progenitor of the House of York.