sentences:  He discovered that ecumenical work was particularly restricted in the context of the Troubles in a diocese lying on both sides of the border between Northern Ireland and the Republic of Ireland, which he accordingly resigned to take up a professorship in Systematic Theology in the Faculty of Theology at Manchester University.During this period he worked notably on the evolution of Christian theology in the period between (and immediately prior to) the Councils of Nicea (325 AD) and Constantinople (381 A. D.) He was the first British or Irish contributor to the Sources Chrétiennes collection of early Christian writings.Among his writings was "Reasonable Belief" which was written jointly with his brother.