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 of England and Wales has five provinces, subdivided into 22 dioceses, and the Catholic Church of 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 Church in Ireland was not divided when civil authority in Ireland was partitioned in the 1920s.
A diocese, also known 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, 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 becoming illegal, there were no Catholic dioceses in England and Wales, with several apostolic vicars, bishops of titular sees governing not in their own name, as diocesan bishops do, but provisionally in the name of the Pope, being appointed instead. However, with the passing of the Catholic Relief Act 1829, legalising the practice of the Catholic faith again, Pope Pius IX recreated the Catholic Church diocesan hierarchy on 29 September 1850 by issuing the papal bull Universalis Ecclesiae. The Hierarchy in Scotland was restored in 1878.
Three Catholic dioceses, those of Leeds, Liverpool, and Portsmouth, share their territorial name with Anglican dioceses, the Anglican Diocese of Leeds, the Anglican diocese of Liverpool, and the Anglican Diocese of Portsmouth respectively. However, in these cases the dioceses cover differing areas.
The Catholic Church in Scotland comprises two Latin ecclesiastical provinces each headed by a Metropolitan archbishop. The provinces in turn are subdivided into 6 dioceses and 2 archdioceses, each headed by a bishop or an archbishop, respectively.
There is an Apostolic Nunciature to Great Britain as papal diplomatic representation (embassy-level) to the British authorities (UK)
|Archdiocese of Birmingham||St Chad's Cathedral||1850|
|Diocese of Clifton||Clifton Cathedral||1850|
|Diocese of Shrewsbury||Shrewsbury Cathedral||1850|
|Metropolitan Archdiocese of Cardiff||Cardiff Cathedral||1850|
|Diocese of Menevia||Swansea Cathedral||1898|
|Diocese of Wrexham||Wrexham Cathedral||1987|
|Archdiocese of Liverpool||Liverpool Metropolitan Cathedral||1850|
|Diocese of Hallam||Cathedral Church of St Marie||1980|
|Diocese of Hexham and Newcastle||St Mary's Cathedral||1850|
|Diocese of Lancaster||Lancaster Cathedral||1924|
|Diocese of Leeds||Leeds Cathedral||1878|
|Diocese of Middlesbrough||Middlesbrough Cathedral||1878|
|Diocese of Salford||Salford Cathedral||1850|
|Archdiocese of Southwark||St George's Cathedral||1851|
|Diocese of Arundel and Brighton||Arundel Cathedral||1965|
|Diocese of Plymouth||Plymouth Cathedral||1850|
|Diocese of Portsmouth||Cathedral of St John the Evangelist||1882|
|Metropolitan Diocese of Westminster||Westminster Cathedral||1850|
|Diocese of Brentwood||Brentwood Cathedral||1917|
|Diocese of East Anglia||St John the Baptist Cathedral||1976|
|Diocese of Northampton||Northampton Cathedral||1850|
|Diocese of Nottingham||Nottingham Cathedral||1850|