The 12th-century and 13th-century church in the south-east corner is more like a miniature cathedral than a typical almshouse chapel. The building is stone-vaulted throughout, with transepts and a central tower. The walls are over a metre thick, made from stone from Caen, Dorset, and the Isle of Wight as well as local flint. The roof is lead. The building is in Transitional Norman/Gothic style. Started in 1135, the chancel was the first part, built two bays deep with aisles. This is typically Norman, with round-headed windows and much chevron ornament. But the main arches in the arcade and beneath the central tower are slightly pointed in the Gothic manner. The three-bay aisled nave and transepts continue the style. Between 1383 and 1385, a large tracery window was inserted in the west front, and the clerestory windows in the nave were enlarged and a north porch added. Several medieval encaustic tiles survive on the floor. There are also traces of medieval wall paintings. The stained glass is mainly 19th century. The font came from the nearby St Faith's Church, which was demolished in 1507.