St Mary's is a flint church with ashlar dressings consisting of a nave with a three-bay N aisle, chancel and W tower with a short spire. The church was rebuilt in 1878 and at first sight it appears to be all of that date, but the S nave wall includes a doorway with a 12thc. arch, and the chancel has pilaster strips suggesting 11-12thc. fabric. The S doorway is the only feature described here.

Walpole was held by 17 free men from Count Alan in 1086, although the Domesday Survey recorded that others also held land there, valued with Bramfield. A church with 16 acres and half an acre of meadow was recorded.

Blyth Valley Team Ministry, i.e. Blyford, Bramfield, Chediston, Halesworth, Holton, Linstead Parva, Spexhall, Thorington, Walpole, Wenhaston and Wissett.

The label decoration is a more sophisticated version of the label of the W window at Westhall. The chevron is identical to that at on the N doorway at Wissett.