St Mary’s in Rickinghall Inferior is a large church, with its 14th century south aisle even wider than the earlier nave. The tower was built in the 12th century, but had the upper part of the circle rebuilt in the 13th century, before the octagonal belfry was added in the 14th century.  The openings in the earlier belfry had pointed arches, and these are now blocked with flintwork, except for the west one, which has a smaller opening inserted in it. The 15th century parapet has pinnacles on the corners, and flushwork panels with shields in the battlements. The north nave has large 15th century windows and the east window in the chancel now has 19th century curving tracery with crowned headstops. The east window of the aisle has panelled tracery, with oak leaves carved in the spandrels of the cusping in the tops of the main lights. This aisle has a diagonal buttress at either end which is topped with a crocketted pinnacle. The south porch has low arcading inside, framing two small Y traceried windows each side with a quatrefoil opening just above them, and stone seats. It was first built in the 14th century, but then had an additional storey added in the 15th century. Above the entrance arch is a stone frieze of IHS and M, uniquely with a separate stone with a crown above the letters.

Entering the south aisle the striking feature is the glass in the east window, inserted in 2000. It shows a large Christ figure above a natural scene. At the bottom, below the two Ms, marking the Millenium, are Roman edible snails, found in this area. Nearby is a 14th century elaborately carved angle piscina, with crocketted finials, though how much is actually due to the 19th century restoration no-one knows. The 14th century font stands at the west end of the aisle, with a variety of flat tracery for window Patterns on the bowl. The arcade is supported on three pillars of quatrefoil plan, with a fillet between the lobes and a keel down the outer edge. Between the arches, on the south side, are some fine head corbels, a king, a queen and a bishop or abbot? The tower arch is 12th century with a stone-framed round arch, with clear diagonal tooling (lines) on the stones (indication of 12th century work). The chancel screen was removed in the 19th century, but some bits of it were used to form the reredos. The 19th century paintings on its show Isaiah, Jeremiah, Matthew, the Three Kings greeting the Christ Child, Luke, John, Ezekiel, Daniel. There is an angle piscina and a dropped-sill sedilia.  The window above these has some medieval fragments of glass and also some made in the 17th century in the tracery.