Bampton’s early development is unclear but by the late 12th century the church was remodeled in a cruciform plan on a very grand scale. The most conspicuous remnants of Norman work can be found in the south transept and include the south doorway and blocked arch in the east wall. The church was remodelled in Early English style in the late thirteenth early fourteen century and further enlarged. C 1250 the tower and spire was raised and a quartet of lifesized figures added to its base. One figure, John The Baptist, now stands inside the church as was damaged by storms in 1991. Further alterations took place between 1290 and 1320 and included rebuilding the nave and adding side aisles and a south west chapel. The ballflower studded west doorway was added in the middle of the fourteenth century. The chancel was remodelled and given a clerestory between 1497-99.

The most interesting part is in the north transept and chancel. The nave has fine arcades of rounded piers and double champhered arches, lit by windows in which the heads of each trio of lancets are outlined by cusped rere-arches. The early herringbone stonework beneath the tower probably dates from the eleventh century and is part of a previous nave.

At the north east of the nave is an odd stair turret that interrupts the span of the final arch and restricts access to the north transept. On the east side is a chapel to St Bernwald, which was previously home to the saints shrine. It retains an empty fourteenth century canopied recess, the matrix of a lost brass and a C.1400 stone effigy of a knight.

From the nave you can have access to a fifteenth or sixteenth century chapel and its collection of wall monuments to the Horde family. In the east wall of the remodelled chancel you can see a fourteenth century reredos of Christ and the Apostles. The chancel contains an impressive Perpendicular Easter Sepulcher in the north wall, a trio of brasses in the floor and some early sixteenth century choir stalls.