Born in Salford, Manchester on 4 May 1917, the son of Fred Barrett, a UM minister, he was educated at Shebbear College and Pembroke College, Cambridge, where he achieved a Double First. He trained for the ministry at Wesley House. In 1942 he became Assistant Tutor at Headingley College and in 1945 Lecturer in NT at Durham University, where he remained until retirement, being appointed to the new post of Professor of Divinity in 1958. He was known and loved as a preacher in the village chapels of the area and was one of four Methodists who signed a Dissentient Statement on the Anglican-Methodist Conversations in 1963.
An internationally renowned scholar, elected President of the Society for NT Studies in 1973, he was awarded honorary doctorates at Hull, Aberdeen and Hamburg, as well as the Burkitt Medal for Biblical Studies in 1966. He was electef Fellow of the British Academy in 1961. His early The Holy Spirit and the Gospel Tradition (1947) was a landmark in the study of the Spirit in the NT; but his most important work is a series of commentaries, notably on John's Gospel (1955), 1 & 2 Corinthians (1968, 1973), Romans (1957) and Acts (1996). In 1961 he gave the Peake Memorial Lecture on 'Luke the Historian'.
He retired in 1982 and in 2007 a fund was established in his honour to perpetuate his influence by providing scholarships or fellowships at Durham to encourage research in biblical studies. He died on 26 August 2011.
'Barrett had been a well-known opponent of the Anglican-Methodist union scheme in the 1960s, which had failed only because the Anglicans did not obrain a sufficient majority in favour of the plan. [Bill Harris's] wife Margaret defended the Church of South India and said: "Our bishops are different from the Church of England bishops; we should not dream of calling one of them My Lord." Kingsley replied: "I should not object to your calling them My Lord; I object to your calling them bishops."'
(A.Raymond George, Memories, Methodist and Ecumenical(Buxton , 2003) pp.46-7)