The present plan of the church was established during the 12th century (apart from the chancel, which was added a little later). However, changes (particularly to the doors and windows) were made during the 13th century, and major development of the north aisle was undertaken in the first half of the 14th century. The tower dates from the 15th century. The South Aisle and the font have been identified as the earliest existing parts of the church (circa 1150′s). The two pillars with decorated capitals separate the aisle from the Nave. The decoration of the east pillar (see picture) has interlacing arcs similar to those on the font.

The Font dating from Norman times, stands on a square base (see picture). In front is a 15th century church wardens’ coffer.

The North Aisle is unique, the most interesting and distinctive feature of Ducklington church, built in the Decorated style between the 1330s and 1370s. The Chancel was added in the 13th century. Five of the original lancet windows remain; the geometrical 3 light window was inserted later.

The Nave, dating from about 1250, is separated from the aisles by the North and South Arcades and from the Chancel by an imposing Arch in the Early English style. The plain truss Roof is very old and has in it three early and primitive dormer windows. It is said to be a good example of an open cantilever roof of the 14th or early 15th century.

The South Aisle, the oldest part of the church, was first built in the Norman period before 1150 and rebuilt in the 13th century in the Early English style. The Tower is of later date, built in the 15th century in the Perpendicular style, as are the plinth and windows. The lower window is square headed with three lights. The upper window is flat pointed with two lights. The stairway which projects on the south side, is also perpendicular in style. The north windows are 13th century Early English lancets. The east window is Perpendicular. The east gable had an Early English cusped triplet window.