In the isle of Jersey and on the coasts of Normandy the name of this servant of God has been in veneration from the time of his death, but little is certainly known of him. He is said to have belonged to Tongres in Belgium, and to have been brought up to Christianity by a priest, Cunibert, who was afterwards murdered by the boy’s heathen father. He then fled for refuge to St Marcou at Nanteuil in the Cotentin. Another tradition says he was converted by this abbot. Seized with an ardent desire of serving God in solitude, Helier retired to the isle of Jersey and, choosing for his abode a cave on the summit of a rock of difficult access, there led an eremitical life of fasting and prayer. In this lonely retreat he was murdered by robbers or infidel barbarians to whom he had tried to preach the gospel. The chief town in the island bears his name and he is commemorated on July 16 in the diocese of Portsmouth, which includes the Channel Islands; his feast is also kept by Rennes and by Coutances, the island having been formerly subject to the jurisdiction of that see.
From Butler’s Lives of the Saints