The Diocese of Llandaff is an Anglican (Church in Wales) diocese that traces its roots to pre-Reformation times as heir of a Catholic bishopric. It is headed by the Bishop of Llandaff, whose seat is located at the Cathedral Church of Saint Peter and Saint Paul in Llandaff, a suburb of Cardiff. It currently covers most of the former Welsh county of Glamorgan, but once stretched from the River Towy to the middle of the Wye Valley. Archdeaconries and deaneries The diocese of Llandaff is currently divided into two archdeaconries: Llandaff and Margam. From 2002–2020 there was a third archdeaconry, that of Morgannwg; in 2020, of its four deaneries, Pontypridd and Merthyr Tydfil & Caerphilly moved to Llandaff, and Cynon Valley and Rhondda moved to Margam. Archdeacons of Llandaff See Archdeacon of Llandaff Archdeacons of Margam See Archdeacon of Margam Archdeacons of Morgannwg 2002–2004 (ret.): Martin Williams 2004–2006 (res.): David Yeoman 2006–2020: Chris Smith Pre-reformation history : Catholic bishopric Legendary foundations Lucius of Britain A number of traditions associate Llandaff with Lucius of Britain. Lucius was believed to be a 2nd century king who first beseeched the Pope (Eleutherius) to convert him to Christianity. The Pope's response was to send a Christian mission to Britain, which would include the building of Britain's first church. The Welsh Triads relate this tradition to Llandaff, stating that Lucius "made the first Church at Llandaf, which was the first in the Isle of Britain." another triad lists ""the three archbishoprics of the Isle of Britain" and states that "the first was Llandaf, of the gift of Lleirwg (Lucius), the son of Coel, the son of Cyllin, who first gave lands and civil privileges to such as first embraced the faith in Christ." Although the Lucius legend is now considered to be pseudohistory, it was recounted by Nennius, Bede and Geoffrey of Monmouth, and seems to have been widely accepted in the medieval period. Four names are associated with the task of executing the Pope's wishes, these include the early Welsh saints Fagan, Deruvian and Elvan. Fagan is sometimes named as "the first Bishop of Llandaff" while all three became patrons of churches and villages throughout the diocese. Iolo Morgannwg also linked these early figures to Llandaff, writing extensively on this supposed early foundation. In the Iolo Manuscripts, he credits Fagan as the second Bishop of Llandaff (succeeding Dyfan, a figure Iolo conflates with Deruvian).