Early Life and Education
Teilo was born around 500 at Penally (Penalun) in Pembrokeshire, Wales. His father is usually identified as Ensich ap Hydwn, and he is described as the brother of Anowed and the uncle of Saints Ismael and Euddogwy.
He received his early education under Dubricius (Dyfrig) and later attended the school directed by Paulinus of Wales at a place recorded as 'Wincdi-Lantquendi,' thought to be Whitland. There he met Saint David and became his close companion. Together with the companions Aeddan and Ysfael, Teilo traveled to Mynyw (St Davids), where David founded his abbey; tradition relates that in doing so they drove out an Irish pirate named Bwya, killing his cattle and burning his fortress.
Bishop of Llandaff
Teilo succeeded Dubricius as Bishop of Llandaff after Dubricius retired to a hermitage on Bardsey Island. He founded the first church at Llandaff, headed a monastic school there, and exercised episcopal authority over the territories of Glywysing and Gwent.
He is also remembered as the founder of a clas, a small monastic settlement, on the site of the present parish church at Llandeilo Fawr, where he died and was buried.
Withdrawal to Brittany
During the plague outbreak of 549, Teilo and a small group of monks left Wales and moved to Dol in Brittany. Accounts place his stay there at approximately seven years and seven months, after which he returned to Wales around 556–557.
His association with Brittany is reflected in the several Breton churches and dedications that bear his name, and in the Breton feast days observed in his honor.
Legacy at Llandeilo Fawr
The monastic settlement Teilo founded at Llandeilo Fawr grew into a place of considerable importance by the early ninth century, with the Church of St Teilo serving as a 'mother church' to surrounding districts. The monastery accumulated extensive estates and housed the Gospel Book of Saint Teilo, one of the finest illuminated manuscripts of early medieval Wales.
Fragments of two large Celtic crosses survive from this period, attesting to Llandeilo's standing as an important ecclesiastical center. The monastery's prominence began to diminish toward the end of the ninth century. Until 1880 the churchyard preserved the saint's baptistery, maintaining his physical connection to the site.
Teilo's cult was widespread: at least twenty-five churches across Wales, Brittany, Cornwall, and Devon bear his name, and he is honored as the patron saint of the city of Cardiff.
Relics & Shrines
A miraculous tradition holds that after Teilo's death his body became three identical bodies, resolving a dispute in which his relics were claimed by three churches: Llandaff Cathedral, Llandeilo Fawr, and Penally Abbey. His skull is preserved in a reliquary in the south chapel of Llandaff Cathedral.
