The church of All Saints in Oystermouth was first mentioned in documents in 1141, when Maurice de Londres received income from it. It was probably built on the ruins of a Roman building and in the 13th, 14th and 15th centuries it was rebuilt successively. In the 19th century, due to the increasing population of the rapidly developing town and the poor technical condition, the church was renovated and expanded with a new northern aisle. In 1915, the Victorian annex was dismantled to make room for the larger new nave and chancel. These works were completed until 1937.
The medieval church consisted of a spacious nave on a rectangular eastern plan, four-sided but slightly narrower chancel, a porch and a tower on the west side. The tower was crowned in a way typical for Wales: a parapet mounted on corbels and a battlement. On the south side, there was a shallow protrusion in the wall with a staircase illuminated by five slit openings. The original entrance to the church was on the south side of the nave. The windows from the 12th / 13th century illuminating the interior were narrow, quite high, topped with pointed arches or trefoils. In the fourteenth, fifteenth and sixteenth centuries, large pointed openings filled with stone traceries, as well as two and three-light windows set in four-sided jambs began to be introduced. The eastern façade stood out with the 14th-century triad of very narrow lancet openings.
As a result of twentieth-century construction works, the medieval church is today the southern aisle and the chapel (former chancel) of a modern temple. The original south entrance to the church is bricked up today. Next to it, a narrow ogival window from the 13th or 14th century has been preserved, and further a three-light window in a rectangular frame from the 16th century. The chancel in the eastern wall has three pointed, narrow windows, originally from the 14th century, but renovated in the 19th century.
Salter M., The old parish churches of Gwent, Glamorgan & Gower, Wolverhampton 2002.
Website britishlistedbuildings.co.uk, Church of All Saints, Oystermouth A Grade II Listed Building in Mumbles (Y Mwmbwls), Swansea.