Patron of two Cornish parishes of this name. No Life of this saint has survived and only the most meagre liturgical evidence. Saints of similar name were venerated in Wales and Brittany, but there is no proof that either should be identified with the other or with the patron of the Cornish parishes. Mawgan may have been abbot of Demetia (Pembrokeshire, now Dyfed) who shared with other 6th-century Welsh saints in the migration over Cornwall and Brittany. Roscarrock makes him bishop of the Isles of Scilly. Sancte Maucanne was invoked in an 11th-century Exeter litany.
From The Oxford Dictionary of Saints in Oxford Reference.