List of Catholic dioceses in Great Britain

The Catholic dioceses in Great Britain are organised by two separate hierarchies: the Catholic Church in England and Wales, and the Catholic Church in Scotland. Within Great Britain, the Catholic Church in England and Wales has five provinces, subdivided into 21 dioceses, and the Catholic Church in Scotland has two provinces, subdivided into 8 dioceses. The Catholic dioceses in Northern Ireland are organised together with those in the Republic of Ireland, as the Catholic Church in Ireland was not divided when civil authority in Ireland was partitioned in 1921.

A diocese, also sometimes known popularly as a bishopric, is an administrative unit under the supervision of a bishop. The Diocese of Westminster is considered the mother church of English and Welsh Catholics,^[1] and although not formally a primate, the Archbishop of Westminster is usually elected President of the Catholic Bishops' Conference of England and Wales, providing a degree of a formal direction for the other English bishops and archbishops.

From the time of the English Reformation in the 16th century, with Catholicism being declared illegal, there were no Catholic dioceses in England and Wales. From 1688, there came to be appointed several apostolic vicars, clergymen in episcopal orders, governing a territory not in their own name, as diocesan bishops do, but provisionally in the name of the Pope. However, with the passing of the Roman Catholic Relief Act 1829,^{[clarification needed]} legalising the practice of the Catholic faith again, Pope Pius IX re-established the Catholic Church diocesan hierarchy on 29 September 1850 by issuing the bull Universalis Ecclesiae. The Hierarchy in Scotland was restored in 1878.

The names of the Catholic dioceses as re-established did not adopt the names of the then existing medieval dioceses, once Catholic and now (in England) Anglican. Four current English Catholic dioceses, those of Leeds, Liverpool, Southwark and Portsmouth, share their territorial name with Anglican dioceses, the Anglican Diocese of Leeds, the Anglican Diocese of Liverpool, the Anglican Diocese of Southwark and the Anglican Diocese of Portsmouth respectively. However, in these cases the dioceses cover differing areas and the Anglican diocese was set up later than the Catholic one.

The Catholic Church in Scotland comprises two Latin ecclesiastical provinces each headed by a Metropolitan archbishop. In addition to the archbishop and his see, each province in turn contains a number of "suffragan" dioceses, each headed by a bishop. In Scotland there are a total of 6 such suffragan dioceses, making overall eight dioceses when the 2 archdioceses are included.

There is an Apostolic Nunciature to Great Britain which is the institutional papal diplomatic representation at full embassy level to the British authorities. The "ambassador", who in fact carries the centuries-old title of "nuncio", has relations with the government of the United Kingdom, and in a different mode with the Catholic bishops of England, Wales and Scotland. He has no dealings with the government of the Irish Republic nor with the Catholic bishops in any part of Ireland. A fellow nuncio, resident in Dublin, is a diplomat accredited to the Irish government and also has dealings with the Irish Catholic bishops both north and south of the border. Other Commonwealth territories are covered by a variety of analogous papal representatives, quite independently of the nuncio in London.