During his life, he was first in line to his father"s throne of England and to his mother"s county of Ponthieu in France. Alphonso was born at Bayonne, in Gascony, and named after his maternal uncle, Alfonso X of Castile, who was his godfather.
At the age of ten, he was engaged to Margaret, daughter of Floris V, Count of Holland. An opulent psalter was being prepared for the marriage when he died, a few months before the wedding was to take place. His heart, however, was buried at the priory of Blackfriars, London (now destroyed).
As heirs-apparent to the throne, both Alphonso and Edward bore the arms of the kingdom, differenced by a label azure of three points.
