Joan Gaveston was born in January 1312 at York. Her father, Piers Gaveston, was supposed to be in exile but he returned to court by Christmas 1311. Edward travelled north, leaving his wife to follow, pausing long enough to collect his heavily pregnant niece Margaret de Clare, Gaveston’s wife, from Wallingford Castle before continuing to York. it’s possible that Piers only intended to see his wife and child before leaving the country but there is no evidence to support the view. Almost immediately after Joan’s birth the king revoked Gaveston’s exile and gave him back his titles and estates. This had the effect of infuriating the barons who had demanded his banishment the previous year.
Five months later Gaveston having fled north to Newcastle before returning south to York found himself under siege in Scarborugh Castle. A short time later he was dead at the hands of the Earl of Warwick and the Earl of Lancaster. Joan, a mere infant, now became a ward of the crown. As her legal guardian, Edward sent the child to Amesbury Priory in Wiltshire. There were a number of royal females in residence at the priory founded by Henry II for the Order of Fontevraud (there were four houses for this order – Amesbury, Westwood, Nuneaton and Grovebury) including Edward’s sister Mary who was a nun. It had a long tradition of providing a home and education for England’s royal women. It had also become the prison for King John’s niece Eleanor of Brittany for a time.
Joan was Gaveston’s sole heir but his lands were problematic given that many of them were crown lands. However, when her uncle, the Earl of Gloucester, was killed at Bannockburn in 1314 she became an heiress. Edward took the opportunity to try and arrange a marriage for her to Thomas Wake of Liddell but he married without Edward’s permission to Blanche of Lancaster the niece of Thomas of Lancaster.
In 1317 Joan, aged five, became betrothed to John Multon the heir to the Lord of Egremont in Cumbria. The king made Lord Wake pay the dowry having married without his permission to Leicester’s daughter. The agreement was that the marriage would go ahead as soon as the two children were old enough.
However, Joan died unexpectedly at the beginning of January 1325 just before her thirteenth birthday.
Kathryn Warner, Edward II: The Unconventional King
Blanche of Lancaster was not the daughter of Thomas but of Henry of Lancaster, Thomas was her uncle
You’re quite right – not sure how that happened. Thomas had no legitimate children.