A legend that King Coel of Colchester was the father of the Empress Saint Helena, and therefore the grandfather of Constantine the Great, appeared in Henry of Huntingdon's "Historia Anglorum" and Geoffrey of Monmouth's "Historia Regum Britanniae". The passages are clearly related, even using some of the same words, but it is not clear which version was first. Henry appears to have written the relevant part of the "Historia Anglorum" before he knew about Geoffrey's work, leading J. S. P. Tatlock and other scholars to conclude that Geoffrey borrowed the passage from Henry, rather than the other way around. The source of the claim is unknown, but may have predated both Henry and Geoffrey. Diana Greenway proposes it came from a lost hagiography of Helena;--> Antonia Harbus suggests it came instead from oral tradition.