After graduating from the University of South California at the end of the Second World War, he came to Oxford via the American University in Cairo, and then on to Cambridge and ordination in the diocese of Ely.

As Fellow and Dean of Emmanuel College and University Lecturer in Divinity, Howard Root was one of those bright stars whom Alec Vidler, as editor of Soundings, drew together in 1966. Root’s essay, the first in the volume, was concerned with the current malaise in natural theology and its remedy. He argued that it was “time to begin all over again” against the criticism of A. J. Ayer and Logical Positivism, on the one hand, and Karl Barth, on the other. It was an eloquent essay.

E. L. Mascall attacked it for discarding much that was precious of the Christian past; but he admired its verve. Perhaps its most interesting aspect was Root’s conclusion that natural theology should be restored by the contemplation of modern literature and the work of contemporary artists who were “in touch with the springs of creative imagination”.

With such promise, he became Professor of Theology at Southampton University in 1966, immediately after the theological and ecumenical stimulation of the Second Vatican Council, where he was one of the Anglican Observers between 1963 and 1965, under Bishop John Moorman of Ripon.

While at Southampton, Root was also for a time a joint editor of The Journal of Theological Studies and a visiting professor at Louvain. Nevertheless, his time at Southampton was not of the easiest, as university cutbacks impinged.

Following from his observation of the Second Vatican Council came Root’s membership of the Anglican/Roman Catholic Joint Preparatory Commission, which reported to the Vatican and the Lambeth Conference of 1968 through its Malta report.

Root and Bishop Moorman contributed a significant paper, “Unity and Comprehensiveness”, to the Preparatory Commission. It concerned itself with problems of doctrinal continuity and development, establishing the meaning of definitions and the question of doctrinal boundaries — questions that have never been absent from the Anglican–Roman Catholic agenda since.

Meanwhile, Root had been invited to chair the Archbishop of Canterbury’s commission on marriage discipline, which eventually resulted in the 1971 report Marriage, Divorce and the Church. As the Bishop of Wakefield has remarked, this was the most theological of a series of reports, all of which suffered a similar fate of non-acceptance by a sufficient majority in the General Synod.

As Root was to note wryly, this left the Church of England (until recently) with the most rigorous theoretical marriage discipline of all Churches, and the most chaotic and undisciplined in practice.

Root became a member of the Anglican Roman Catholic International Commission (ARCIC-I) in 1970. In the few interstices between theological discussion, Howard would be found avidly working on the Times crossword with fellow members of the Commission. ARCIC-I completed its work in the Final Report (1981).

That year, he moved to Rome to be Director of the Anglican Centre and the Archbishop of Canterbury’s Counsellor on Vatican Affairs — the Archbishop’s representative in Rome. Wonderfully supported by his wife Celia, both domestically and administratively, Root’s work as an Anglican ambassador in the centre of the Roman Catholic Church’s structures was a ministry characterised by friendship, hospitality, and understanding.

Those who worked in the Pontifical Council for Christian Unity (formerly the Vatican Secretariat for Promoting Christian Unity) trusted him and held him in great esteem. But this was a difficult time for Anglican-Roman Catholic relations: the Congregation for the Doctrine of the Faith distanced itself from the ARCIC report, on the one hand, and the Anglican Communion ordained women priests and eventually bishops, on the other. Root, though theoretically in favour of the ordination of women, did not believe that the time was right.

Equally, the Anglican Consultative Council was to indicate increasingly that the Communion as such would no longer support the Centre financially. Difficulty of access to the Centre was also a serious problem, to be overcome only in more recent years. Friendships in the Gregorian University, where he was a visiting professor, and the Angelicum compensated.

In retirement in Winchester, Root, ever supported by Celia, retained his gentle openness and friendship to all, despite illness. But there must be a sadness that things that might have been never came to pass. His memory will be cherished with affection.