Margaret of England was the tenth child and seventh daughter of King Edward I of England and his first wife, Eleanor of Castile. Her husband was John II, Duke of Brabant, whom she married in 1290, the year of her mother's death. Margaret and John had one child, John III, Duke of Brabant.

Eleanor of Castile was Queen of England as the first wife of Edward I. She was educated at the Castilian court and also ruled as Countess of Ponthieu in her own right from 1279. After diplomatic efforts to secure her marriage and affirm English sovereignty over Gascony, 13-year-old Eleanor was married to Edward at the monastery of Las Huelgas, Burgos, on 1 November 1254. She is believed to have birthed a child not long after.