The exact date of the construction of the church is not known, but probably the oldest part of it, may come from the twelfth century. In the sixteenth century, the chancel was rebuilt, and the side chapel was added in the 17th century. Originally, the church was a chapel of ease of the church in Llanbeulan, but it lost its importance when Tal y llyn village disappeared, probably after the period of the fourteenth-century plague. The building underwent minor modifications in the eighteenth and nineteenth centuries.
The church was originally a simple, rural building consisting of an aisleless nave, built on a rectangular plan with dimensions of 7.6 x 4 meters, and a late-medieval presbytery measuring 5 x 3.4 meters. A simple entrance portal was placed in the west facade. Between the nave and the presbytery there was an arcade with a slightly shaped ogee arch, probably rebuilt in the 16th century. The interior was covered with an open, wooden roof truss with slightly curved collar beams and massive rafters.
The church is a rare example of a simple sacral building that has survived to the present day without major changes. The early modern modifications only affected the window openings, and a small chapel was added to the southern wall of the chancel already in the post Middle Ages period, but it did not differ stylistically from the rest of the building. The 16th-century three-light window in the eastern wall of the presbytery is the only original opening. The roof truss inside the church dates back to the 15th and 17th centuries. The octagonal baptismal font from the 15th century is also noteworthy.
Salter M., The old parish churches of North Wales, Wolverhampton 1993.
Website wikipedia.org, St Mary’s Church, Tal-y-llyn.