[4] Joan may have been born in France, and probably spent part of her childhood there, as King John had her brought to England from Normandy in December 1203, in preparation for a marriage alliance to Prince Llywelyn ap Iorwerth.

Joan was betrothed to Llywelyn the Great in 1204, and the marriage is thought to have taken place in 1205, although some of the annals of the abbey of St Werburgh in Chester say that it occurred in 1204.

"[1] In April 1226 Joan obtained a papal decree from Pope Honorius III, declaring her legitimate on the basis that her parents had not been married to others at the time of her birth, but without giving her a claim to the English throne.

Llywelyn's great grief at her death is recorded; he founded a Franciscan friary in her honour on the seashore at Llanfaes, opposite the royal residence.

Above the empty coffin is a slate panel inscribed: "This plain sarcophagus, (once dignified as having contained the remains of Joan, daughter of King John, and consort of Llewelyn ap Iorwerth, Prince of North Wales, who died in the year 1237), having been conveyed from the Friary of Llanfaes, and alas, used for many years as a horsewatering trough, was rescued from such an indignity and placed here for preservation as well as to excite serious meditation on the transitory nature of all sublunary distinctions.