Claydon, meaning clayey hill, is the most northerly parish in Oxfordshire, and the small ironstone church stands at its highest point. It consists of chancel, nave, N aisle and N chapel, and a low W tower with a saddleback roof. There is no division between nave and chancel. The original church had a 12thc. nave and N aisle. The chancel has been so altered that its original date is difficult to determine. Most changes took place in the 13thc. when a N chapel was also added to it. The Romanesque features are the S nave doorway, much restored, and the nave and N aisle, separated by an arcade of three bays. The capitals of the two short piers are decorated on the nave side only.

Claydon was originally a chapelry of nearby Cropredy, where the Bishop of Lincoln held a large manor recorded in Domesday Book. In 1851, Claydon joined the chapelry of Mollington and formed a separate benefice. In 1996 these parishes joined with Cropredy, Great Bourton and Wardington to form the Shires Edge Benefice. The Three Shire Stones (the point where the boundaries of Oxfordshire, Northamptonshire and Warwickshire meet) are less than one mile away.

Sherwood and Pevsner (1974) call this church small and primitive. The capitals of the N aisle piers are decorated only on the inner sides. This suggests that funds were limited and possibly the quality of the stone was poor as some of the carving, although acceptably executed, has suffered damage. The mismatch between the round capitals and the square imposts is a different problem. Perhaps the chamfering at the impost corners, making them almost octagonal, was intended to correct this defect. The church at Sandford St Martin, in W Oxfordshire, has Transitional pointed arcades with two short piers with square chamfered imposts that form irregular octagons, and they now surmount octagonal columns that may have been cut down from round ones.

VCH date the nave and N aisle as 12thc., whereas Sherwood and Pevsner (1974) suggest the arcades are Transitional. This is consistent with the stiff-leaf decoration of the capitals, but round-headed or segmental arches at this time seem rather unusual.