 Gilbert de Clare was the son of Gilbert de Clare, 7th Earl of Gloucester – known as Gilbert 'the Red' – who in 1290 married Joan of Acre, daughter of Edward I. As a condition for the marriage, the earl had to surrender all his lands to the king, only to have them returned jointly to himself and his wife for the lifetime of either. This grant was made on the condition that the lands would pass to the couple's joint heirs, but if they were childless to Joan's heirs from any later marriages. The younger Gilbert was born the next year, around 10 May 1291, securing the inheritance for the de Clare family, but his father died only four years later, on 7 December 1295, while the boy was still a minor. Because of the joint enfeoffment, Joan kept the custody of the family lands, and did homage to the king on 20 January the next year.
