stylistic:style_transfer, quality:corruption
Geoffrey of Monmouth's Historia

During the medieval period, Britons regarded Constantine as a king of their own people, particularly associating him with Caernarfon in Gwynedd. While some of this is owed to his fame and his proclamation as emperor in Britain, there was also confusion of his family with Magnus Maximus 's supposed wife Elen and her son, another Constantine (Welsh: Custennin). In the 12th century Henry of Huntingdon included a passage in his Historia Anglorum that the Emperor Constantine's mother was a Briton, making her the daughter of King Cole of Colchester. Geoffrey of Monmouth expanded this story in his highly fictionalised Historia Regum Britanniae, an account of the supposed Kings of Britain from their Trojan origins to the Anglo-Saxon invasion. According to Geoffrey, Cole was King of the Britons when Constantius, here a senator, came to Britain. Afraid of the Romans, Cole submits to Roman law so long as he retains his kingship. However, he dies only a month later, and Constantius takes the throne himself, marrying Cole's daughter Helena. They have their son Constantine, who succeeds his father as King of Britain before becoming Roman emperor.

Historically, this series of events is extremely improbable. Constantius had already left Helena by the time he left for Britain. Additionally, no earlier source mentions that Helena was born in Britain, let alone that she was a princess. Henry's source for the story is unknown, though it may have been a lost hagiography of Helena.