The parish of Forncett St Mary, the smaller and more northerly of the two Forncetts, lies in central southern Norfolk about 9 miles south of the city of Norwich. Forncett St Mary sits, in lanes, about 3 miles to the west of the A140 road which links Norwich with Ipswich and just west of the Norwich to London railway line. Forncett St Mary is a rather small place today little more than a straggle of farms and cottages along the narrow lane which parallels the course of the nearby River Tas. The area is largely agricultural and although a few pastures lie in the Tas valley bottom the majority is devoted to arable crops. The parish covers barely 900 acres and is around half the size of its neighbour, the population reflecting the relative sizes of the two as well.

St Mary's church is now redundant for worship and is maintained by the Churches Trust. Pevsner describes it as "redundant and forlorn" and when I visited the undergrowth was such that it prevented easy access to photograph from more than a single angle, the churchyard is left to nature. The church has early origins, the basal portion of the tower being dated to the 13th century, the tower top and nave are largely Perpendicular and mid 15th century whilst the chancel was rebuilt in 1869 as part of a general restoration. The church sits behind properties and is accessed on foot by (at my visit) a rather overgrown footpath - beware of nettles and brambles - a sad fate for the building.