The church is 12thc in origin. It has alterations and additions from every subsequent century and was thoroughly restored by James Park Harrison in 1843-47 (Verey (1970), 96-97; Verey (1957), 173-78). The surviving 12thc work comprises the chancel arch piers, capitals, and imposts; the exterior corbel table of the chancel now partly within the organ chamber and vestry; a string course; the N doorway; and two windows plus fragments reset into the 19thc E wall of the organ chamber. One of these reset Norman windows, as well as a 13thc two-light window in the nave, was brought from Daglingworth church during the restoration of the latter in 1845 (Keyser (1918-19), 150-53).

Barnsley belonged to the bishopric of Worcester before 822. In 1086 it was held by Durand along with three hides and one yardland as part of the manor of Bibury from the Bishop of Worcester (VCH, 13). The church was built by 1151 and was originally a chapel to Bibury (Cartulary of Oseney Abbey, 26-70).

The simple sawtooth string course (1) reset in the 19thc E wall of the organ chamber may be that removed from the N chancel wall when the vestry was added; it is identical to the string course remaining in the vestry. The chevron voussoir also reset in the E wall of the organ chamber may be from the arch of the blocked S doorway. The undecorated face of the impost of the large corbel reset in the same wall suggests its possible use as a terminal corbel supporting posts for a timber roof.