Originally dedicated to God and St Alban, St John's is a Grade II* listed medieval church in the Early English style. The church comprises a nave and chancel, with a west tower containing five bells.
The nave is the oldest part of the church, dating from the early C14th while the chancel was rebuilt at the end of that century by Abbot John de la Moote of St Albans (1396-1401). The ashlar faced tower dates from around 1500 when the nave walls were heightened to allow the installation of new tall Perpendicular style windows.
St John's was restored in 1881 by Sir Gilbert Scott.
Pipistrelles and brown long-eared bats use the church as a place to roost during the day, with droppings and urine staining mostly confined to the chancel.
Coverings protect sensitive items such as the altar and altar rail, and extra cleaning is required to keep on top of the bat mess.
In June 2023 the project ran a school workshop looking at the issue of bats in churches with a nearby school at St Mary’s, North Marston which also shelters a small number of bats.