Joan was born circa 1191 as the illegitimate daughter of King John of England and a woman named Clemence. We know her mother’s name as it was mentioned in Joan’s obituary where she is called Regina Clementina, though there is no evidence of a Queen Clemence. He was legally married to Isabella, Countess of Gloucester at the time of Joan’s birth in 1191 and that marriage was annulled in 1199, shortly after he became King. Joan was probably born in France and spent most of her childhood there. We know that she came to England in December 1203 from Normandy to prepare for her wedding to Prince Llywelyn ab Iorwerth. They married sometime between that December 1203 and October 1204, and the wedding was celebrated at St. Werburgh’s Abbey in Chester (now Chester Cathedral). They had two children that can be confirmed. There are several others that could be hers as well.
She was declared legitimate by papal decree in April of 1226, though this came without a claim to the English throne. This was used to strengthen her son’s claims to his father’s lands, as he had an elder half-brother.
In 1230 she was caught up in an affair. During Easter William de Braose, who was at the time her husband’s prisoner, was discovered with her in her husband’s bed-chamber. For this, he was hanged on 2 May 1230. Joan was placed under house arrest, though she was forgiven just 12 months later and she may have given birth to a daughter in early 1231. William de Braose’s daughter Isabella was set to marry her son, Dafydd and surprisingly, this marriage went ahead as planned after a letter from William de Braose’s wife, Eva.
Joan was known as the Lady of Wales. It was her son who first used the title Prince of Wales. She died in 1237, and her husband’s grief was great, despite the problems of 1230. He founded a Franciscan friary in her honour, which unfortunately was destroyed during the dissolution of the monasteries. Her stone coffin survives, luckily.
Her great-granddaughter was Gwenllian of Wales.