Margaret de Clare, Countess of Gloucester, Countess of Cornwall (12 October 1293 – 9 April 1342) was an English noblewoman, heiress, and the second eldest of the three daughters of Gilbert de Clare, 6th Earl of Hertford and his wife Joan of Acre, making her a granddaughter of King Edward I of England.
According to the Vita Edwardi Secundi, this marriage was arranged by the King "to strengthen Piers and surround him with friends".
The marriage of such a high-born heiress to a foreigner did not please the English nobility and engendered a great deal of unpopularity.
[5][1] It is alleged that they had another child named Amy Gaveston born around 1310, but there is little evidence outside of hearsay to validate this claim.
Her dower rights as Countess of Cornwall were disputed, and so King Edward instead assigned her Oakham Castle and other lands.
Margaret died on 9 April 1342, and her sister Lady Elizabeth de Clare paid for prayers to be said for her soul at Tonbridge Priory in Kent, England, where she was buried.