Welsh biblical scholar, he was born at Barmouth, Merioneth. He was educated in the local County Intermediate School, and later at Headingley College and the University of Leeds. After a short period as Assistant Tutor at Headingley, in 1953 he became Tutor in New Testament at Hartley Victoria College and Lecturer in the Faculty of Theology in Manchester University. From 1969 he was Senior Lecturer in Biblical Studies in the University College of North Wales, Bangor. In retirement he has been an active Supernumerary in Anglesey and Gwynedd. He has published many books and articles in both Welsh and English in the field of biblical studies, including The Gospel According to St. John (1964), Saints in Christ Jesus (1975) and an edition of The Passion Narrative of St. Luke by Vincent Taylor. He delivered the Peake Memorial Lecture, On Translating the Bible (1975). His most notable achievement was as Director of the new Welsh translation of the Bible from the original texts; Y Beibl Cymraeg Newydd was published in 1988, exactly 400 years after the first and only previous translation of the whole Bible into Welsh. He subsequently edited a concordance to the translation, Mynegair i'r BCN (1998). He edited Gwarchod y Gair (1993), the memorial volume in honour of Griffith T. Roberts. He received an honorary DD from the University of Wales in 1989.