By dint of his particularly detailed research over many years he became the prime authority on the history of the translation of the Scriptures into Welsh. His volume, Y Testament Newydd Cymraeg 1551-1620, appeared in 1976, which earned him the DD degree of the University of Wales, and then he completed his studies in the field by the year of the celebration of the four hundredth anniversary of Bishop William Morgan's translation in 1988, Yr Hen Destament Cymraeg 1551-1620. He was awarded the Vernon Hull Memorial Prize by the Board of Celtic Studies twice for these masterpieces of research. Professor J. E. Caerwyn Williams wrote of him: ‘He completed a task which sorely needed to be done, and he effected it in such a way that it will never again be needed to be done, so that all interested in Welsh and the Welsh Bible will be indebted to him.’ He also published bilingual books which conveyed the results of his researches in a less detailed and technical manner: William Salesbury and His Testament to commemorate the four-hundredth anniversary of the publication of the first full translation of the New Testament into Welsh in 1967, and William Morgan and His Bible, for the celebrations of 1988. In addition he published a number of articles in composite volumes and journals detailing his researches. He did much of this work whilst holding the Margaret Eilian Owen Fellowship in the National Library from 1973 to 1985. He was invited to read a paper outlining his research to the International Society for New Testament Studies in Durham in 1978. He was a member of the Panel for the translation of the New Welsh Bible from the outset in 1964 until it was completed in 1988.
He wrote other books in addition: Hanes Cristnogaeth (1949), Arweiniad Byr i'r Testament Newydd (1963), Elfennau Groeg y Testament Newydd (jointly with Owen E. Evans, 1975), and Trosom Ni: Nodiadau ar Drefn y Cadw yn yr Ysgrythurau (1991). A Festschrift, Efrydiau Beiblaidd Bangor 3 (ed. Owen E. Evans), was presented to him on the occasion of his retirement in 1978. His papers are in Bangor University Archives.
He married Sibyl Jones, Treorchy, and a daughter, Mari, was born to them; she died at the age of forty in 1984. His wife, Sibyl, died 1 February, 2004, and Isaac Thomas died in Bangor on 23 May, 2004.
John Tudno Williams, Aberystwyth
Published date: 2013