Baylham stands in wooded arable land among rolling hills midway between Ipswich and Stowmarket. The church stands in the centre of the village and Baylham Hall is 0.7 miles away to the W. St Peter's is a flint church of nave, chancel with N and S transepts and W tower. The N nave doorway indicates the 12thc. origin of the fabric, but new windows were installed on the S in the 14thc. and on the N in the 15thc. All were restored in the 19thc., and the S doorway and its porch are 19thc. too. The chancel was rebuilt by Frederick Barnes in 1870, including the chancel arch, and both transepts were added at that date. The N transept houses the organ and a vestry, and the S is fitted with pews but no altar. The tower is unbuttressed and of knapped flint; perhaps 13thc. in origin but remodelled and heightened in the 14thc. It has small lancets high in the lower storey and a 14thc. W window and bell-openings. The parapet is battlemented. The blocked N doorway is the only Romanesque feature.

Baylham was held as a manor by Munding, a free man commended to the Abbot of Bury, before the Conquest. In 1086 it was held by William de Bournville from Roger Bigod. It consisted of one carucate of ploughland with half a church with 12 acres. William also held other small parcels in the same place that had been held by others before the Conquest.

Benefice of Great and Little Blakenham with Baylham and Nettlestead.

The tympanum of the N doorway has a central field bounded by a raised fillet, and this is also found on the famous boar tympanum in St Nicholas, Ipswich. True opus reticulatum occurs in Suffolk on tympana at Wissington and Ousden.