The advowson of Chilbolton has been in the hands of the Bishops of Winchester since the manor itself was granted to the church by King Atheistan and the church existed at the time of Domesday.
The name “St Mary-the-less” is somewhat of a mystery and it is not really known to which St Mary the church is dedicated. Canon Marsh, one time Rector of Chilbolton, gives one possible explanation which lies in the fact that the church of St Mary the Virgin, Bath was, in the 11th and following centuries, responsible for the maintenance of the Benedictine Nunnery of Wherwell, until the dissolution of the monasteries. Chilbolton church was build in the 12th century close to the Wherwell Monastery and so was called St. Mary-the-less, the parent church of St Mary the Virgin being at Bath. A more recent and perhaps more likely possibility is that when the Parish church in Andover had its dedication changed from St Peter to St Mary in the 14th Century, Chilbolton Church, being in the same deanery, had to step down and become St Mary-the-Less.
Extensive alterations have been made over the ensuing years.
In 1842 the old bell tower which stood upon massive oak-tree props at the rear of the nave in front of the West window was taken down and rebuilt in its preseilt position. A gallery extending half way up the church was also removed “by which means the west window was made available for lighting and beautifying the Church”
In the 15th century the church had a ro loft, the stairway to which was still in place according to a survey iii 1908, this no longer stands at the north east angle of the nave, but the priests opening in the wall high above the pulpit is clearly seen.