St James's has a nave with three-bay N and S aisles and a modern S porch, an aisleless chancel, lengthened in the 13thc., with a N vestry, and a W tower added c.1400. Its octagonal spire was blown down by a gale in 1741 (as was that of All Saints in St Ives, nearby), and what was left was levelled off and decorated with ball finials at the angles. The piers and the central bay of the N arcade are 12thc. and described below. The W bay arch is stylistically later, and could have been rebuilt when the tower was added. At this time the W bay of the nave was shortened, so that the W arches of both arcades die into the wall without responds or capitals. The N arcade, E bay also looks to have been rebuilt, but rather earlier, by fitting a new E respond capital and half of the pier 1 capital along with a new arch. Something similar happened on the S side, which has round arches in the two W bays, but a pointed arch in the E bay. Both piers and the E respond are original, and all capitals are moulded, suggesting an original construction date for the S arcade in the 13thc.
The bizarre arrangement of the arcades is perhaps most satisfactorily explained by the hypothesis that the church originally had a central tower, which was removed in the 13thc. but not replaced with a west tower until c. 1400. There is no very obvious evidence for this. Locally, the replacement of a central tower with one at the west is known from Soham and Great Wilbraham (both Cambs). On the N wall of the chancel is a 12thc. double aumbry. It is completely plain, so not described here, but a photograph is included.
