The earliest
Life of Petroc states that he was a younger son of an unnamed Welsh chieftain: the twelfth century version known as the
Gotha Life, written at Bodmin, identifies that king as
Glywys of
Glywysing (Orme 2000, p. 215) and Petroc as a brother of
Gwynllyw and uncle of
Cadoc. He studied in Ireland, where later he is said to have been the teacher of
Kevin of Glendalough. Petroc ministered throughout
Dumnonia, which centred in Dewnans (Devon), and included Kernow (Cornwall), Somerset and Dorset. He also served in Brittany. Petroc founded churches in Little Petherick and in many parts of Britain, Wales and Brittany. He is said to have converted
Constantine of Cornwall to Christianity by saving a deer Constantine was hunting. ==Veneration==