Sanctus bell, sanctus bell window. A bell rung at the consecration during Mass. In medieval practice, it was probably one of the bells in the tower, rung by an observer on the ringing platform - hence, the sanctus bell window in the west wall of many naves. Sometimes, the replacement of a roof in the 19th century has meant this being left above the roofline, exposed to the open air.

It called the attention of people at work in the fields or town to what was happening, enabling them to stop and pray for a moment. Some sanctus bells were located in the chancel, or in a sanctus bell turret above the nave.