The editors acknowledge with gratitude the guidance of Cressida Williams at Canterbury Cathedral Library and staff at Lambeth Palace Library in London. The work has been much encouraged by Margaret Pawley and by Virginia Johnstone, who typed most of the reports in Rome. It has also been greatly assisted by many conversations with other scholars and thinkers, particularly those who came to discuss Vatican II in its ecumenical context at a colloquium in George Bell House, Chichester Cathedral, in June 2013. The editors take full responsibility for any errors or omissions.

Charles de Gaulle famously called the Second Vatican Council the most important event in modern history. Many commentators at the time saw the Council as nothing short of revolutionary, and the later judgements of historians have upheld this view. The astonishing enterprise of a man who became, quite unexpectedly, Pope John XXIII in 1958, this purposeful aggiornamento of the Roman Catholic Church was almost at once a leviathan of papers, committees, commissions, and meetings. Scholars have been left to confront no less than twelve volumes of ‘ante-preparatory’ papers, seven volumes of preparatory papers, and thirty-two volumes of documents generated by the Council itself. A lasting impression of the impressiveness of the affair is often conveyed by photographs of the 2,200-odd bishops of the Church, drawn from around the world, sitting in the basilica of St Peter, a vast, orchestrated theatre of ecclesiastical intent. For this was the council to bring the Church into a new relationship with the modern world, one that was more creative and less defiant; a council to reconsider much – if not quite all – of the theological, liturgical, and ethical infrastructure in which Catholicism lived and breathed and had its being.

The 167 reports which Bernard Pawley sent to London between 1962 and 1964 present an editor with a sum of almost 240,000 words. This length lies beyond the scope of the present series. Accordingly, fairly extensive cutting has been necessary and the criteria which have been applied by the editors should be clearly stated at the outset.

In October 1958 Cardinal Angelo Roncalli was elected Pope. He took the name John XXIII and in January of the following year he announced that he intended to convoke an ecumenical council. John XXIII pursued two aims in calling the council: first, he wished to promote ‘the enlightenment, edification, and joy of the entire Christian people’; secondly, he wished to extend ‘a renewed cordial invitation to the faithful of the separated communities’. John XXIII died after the first session and his successor, Paul VI (1963–1978) continued the work of the Council and presided over the final three sessions held in 1963–1965.

The first document that emerged from the Council, in December 1963, was Sacrosanctum Concilium (Constitution on Sacred Liturgy) and it set the tone for the rest of the Council's work. The initial document still insisted on the primacy of Latin in the liturgy and the priest continuing to turn his back to the worshippers.

When the second period of the Council opened in September 1963 Paul VI had replaced the deceased John XXIII as the Roman pontiff. During this period the discussion on Lumen Gentium continued and the Council Fathers also began discussing Unitatis Redintegratio (Document on Ecumenism).

The Council reopened on 14 September 1964 and the Pope concelebrated mass with twenty-four others from nineteen different countries. The next day the Council returned to the revised text of Lumen Gentium. The bishops confirmed the Church as a ‘divine mystery’ going beyond comprehension and therefore it could not be precisely defined. The document now stressed the important role of local and provincial councils throughout history and held up the model bishop as one who collaborated with the priests and the laity. Although the bishop was still in charge, the document stressed the horizontal dimension of the relationship between bishop, priest, and layman.

Paul VI made two surprising announcements during his opening speech at the fourth and concluding period of the Council: he would create a Synod of Bishops (but reaffirmed that their role was only an advisory one) and he would visit the United Nations during this period to proclaim the Council message of love, peace, and justice.

Bishops and archbishops are of the Roman Catholic Church unless otherwise noted (except for the Archbishops of Canterbury).