Juan I de Inglaterra
He was the son and heir of John de Lacy, jure uxoris Earl of Lincoln (c. 1192–1240) 8th Baron of Halton, 8th Hereditary Constable of Chester, and feudal baron of Pontefract. His father was one of the 25 barons who forced John, King of England to sign Magna Carta in 1215. Edmund's mother was Margaret de Quincy, suo jure Countess of Lincoln (c.1206–1266).