The church comprises nave and chancel and a turret at the W end of the nave (to give access to the bells). The church was originally 12thc. in its entirety but the chancel was rebuilt in the 14thc. and the S porch added in the 18thc. Archaeological evidence demonstrates that there was probably an earlier church on this site (see VII). The church is covered in render apart from the E angles of the nave which are brick.

At the time of DS Robert de Limesey held the manor of Bygrave. VCH records that the church was given to St Albans Abbey by William de Wedona.

The thick roll in the arch suggests that the doorway may orginally have been of early date, and it would probably have been round-headed before being distorted into its current shape.

The church guide records that late Anglo-Saxon pottery was found in excavations carried out at the site in 1993, and suggests that the nave walls were rebuilt over Saxon walls. Romano-British pottery fragments were found near the N nave wall, suggesting that a structure from this period may have existed in the same area, and Pevsner states that the bricks in the E angles of the nave are Roman.

The E end of the original 12thc. chancel was also excavated in 1993, but no detailed information was available.