He was born in Swansea on 1 July 1944, educated at Belmont Abbey School and studied history at the University of Hull.
His degree included research on the ecclesiastical history of Hereford and, after graduating, Professor Yates began to establish a career as a medievalist with research fellowships at the universities of Exeter and Southampton. When promotion proved hard to come by, he switched track and became an archivist in Carmarthen, North Tyneside, and later at the Portsmouth City Archives. He became Kent's archivist in 1980, aged 36.
Professor Yates combined his duties with research on ecclesiastical architecture, which culminated in his book Buildings, Faith and Worship: Liturgical Arrangement of Anglican Churches, 1600-1900 (1991).
He took early retirement in 1994 and moved to Blandford Forum, after his wife Paula was nominated as the Liberal Democrat candidate for Devon North. There he published another major volume, Anglican Ritualism in Victorian Britain 1830-1910 (1999).
It was only when he took up a post as senior research fellow at the University of Wales, Lampeter, in 2000 that he was able to resume his long-curtailed academic career and widen his range of research interests.
Appointed professor of ecclesiastical history in 2005, he maintained a pattern of producing a solo work, and often an edited volume as well, each year: The Religious Condition of Ireland 1770-1850 (2006); Eighteenth Century Britain: Religion and Politics 1714-1815 (2007); Liturgical Space: Christian Worship and Church Buildings in Western Europe 1500-2000 (2008); and Preaching, Word and Sacrament: Scottish Church Interiors 1560-1860 (2009).
Alongside this scholarly productivity, Professor Yates served as provincial archivist to the Church in Wales and as Lampeter's research director. By establishing a number of research institutes, he hoped to give the university the critical mass it required to do well in the research assessment exercise. He lived long enough to take pleasure in the fruits of his labour, and his own publications undoubtedly helped Lampeter's Department of Theology and Religious Studies do well in the most recent RAE.
"Many of us have been enriched by his scholarly enthusiasms and advised from his expertise in working with students at all levels," recalls Dr Rob Warner, head of the department. "He was not only admired as a scholar and senior colleague, he was also loved as a very dear friend."
Diagnosed with cancer in 2007, Professor Yates continued working until last autumn. He died on 15 January and is survived by his wife, Paula.