Saint Gwynno, also known as Gwynnog ab Gildas, is honored as a sixth-century Welsh saint and confessor. Vatican archives record his festival on 26 October and note a sacred well, Ffynnon Wyno, connected with Llanwonno in Glamorganshire. Tradition presents him as the son of Cau, called Euryn y Coed aur.
In the time of the Yellow Plague of 547, the monks of the late Saint Illtud sought safety from West Wales in Brittany. Rather than return to Pembrokeshire, they moved east into Glamorgan and settled at Llantwit Major (Llanilltud Fawr). Among Illtud's disciples and associates who accompanied them were Bretons, and Gwynno is numbered with them.
The Celtic bishop Saint Dyfrig founded three centres of learning in south-east Wales—at Llancarfan near Cowbridge, at Caerworgorn (now Llantwit Major), and at Caerleon. Gwynno was among the early members of the community at Llancarfan. Under the name Gwynno he is counted one of the three founders of Llantrisant in Glamorganshire, together with Illtyd and Dyfodwg; the chapel of Llanwynno under Llantrisant is dedicated to him.
At Llanwonno the farmhouse called Darwonno (Daearwynno, "Gwynno's land") stood near the church; local memory holds that Gwynno may have lived there and held the surrounding ground, though it is not certain whether the name marks the saint's own holding or a later endowment of the church. No miracles are recorded of him, no writings survive, and the place of his grave is unknown; yet his name and the churches that bear it stand as lasting witness to his work.
Llanwnog in Montgomeryshire also claims him as founder under the form Gwynnog. In the chancel window of that church he is shown in painted glass in episcopal habit, with mitre and crosier, and beneath the figure an old English inscription reads: "Sanctus Gwinocus, cujus animae propitietur Deus. Amen." He is not to be confused with Gwenog, the virgin saint of Llanwenog in Cardiganshire.
May Saint Gwynno intercede for us, and may we imitate today his quiet perseverance in planting the faith where God places us.