A Benedictine Priory was built on the site of an old Saxon church in 1135 in a cruciform shape with a central tower. The building was extended further in the 14th century, with parishioners using the western part of the church for worship, while the Priory had exclusive use of the eastern side of the building.
However, in 1378, tempers flared in a very non-Christian way, between the monks and the parishioners, leading to rioting. King Richard II's (1377-99) solution was to order a wall to be built across the building to separate the parts serving the different communities, and this wall now stands as the east wall of St Mary's. With the Dissolution of the Monasteries in 1536, it was then a simple job demolish the priory buildings while leaving the parish church standing.
The west tower, south porch, south chapel, and rood loft stair turret were added earlier in the 15th century. The building is Grade I listed.