As implied by the place-name, the village is a principal settlement in the valley of the Chew, a tributary of the Avon — which it joins at Keynsham, 10kms NE. As a wealthy possession of the bishops of Bath and Wells before and after the Conquest, it was called ‘Chew Episcopi’ or ‘Bishops Chew’ between 1062 and 1548. Occupying a site where the river is turned from a northerly to an easterly course by the massive Limestone of Dundry Hill to the N of the village, and almost surrounded by tributary streams joining the Chew from W and N, Chew Magna is the focus of a bewildering web of lanes: road communication is possible in any direction (even over Dundry Hill, 150m higher), although the main route nowadays will be the B3114 or the B3130, which two roads meet in the village, the former running S past Chew Valley Lake towards the A368 between Bath and Weston and the latter running approximately E-W between the A37 and A38 trunk roads. The B3114 is also the route one would take to cross Mendip to reach Wells. Railways hardly come into the picture (except that nearby Bristol, of course, is an important hub). The GWR branch line between Bristol and Radstock closed in 1959; the station nearest Chew was Pensford (4kms E).

Now that local industries (wool etc.) have gone, leaving however plenty of local pastoral and dairy farming, Chew Magna is described as a dormitory for Bristol (the city centre being only about 10kms N) and Bath (about twice that distance E). Also, since the construction of Chew Valley Reservoir/Lake between 1950 and 1956, the area has become a focus for leisure activities. The lake dam is less than 2kms S of the village.

In common with most settlements in this valley (or, indeed, probably anywhere in this area), Chew Magna rests on Triassic bedrock, Mercia Mudstone (formerly called Keuper Marl).

The church, about 300m N of the river, occupies quite a spacious site at an altitude of about 40m above OD. It consists of a chancel with N and S chapels and a N vestry, an aisled nave with N and S porches and a W tower. A good deal of 12thc material has been used in the construction of the curious S doorway, indicating the presence of a church here at that time; otherwise the earliest fabric is the 13thc S arcade, and most of the remainder is Perpendicular in style. Bequests were recorded in 1443 for the N aisle and in 1541 for the tower. The vestry was added in 1824. There is also a 12thc font.

Chew Magna was held by the Bishop of Wells before the Conquest and in 1086. It was a large manor of 30 hides, partly in demesne and partly held by villeins and partly by major tenants, notably Richard, who held 5 hides, Roghard (6 hides), Stephen (5 hides), Aelfric of Stowey (7 virgates) and Wulfric (2 hides). In total the Domesday Survey lists more than a hundred people, which must equate to a total population of around 500.

The manor remained in the hands of successive bishops until the Reformation.

Evidently a rich settlement, Chew Magna is likely to have had a relatively ambitious post-Conquest church. The doorway, reset in the later aisle wall, is unlikely to have originally been of this unusual form, although the impost and label mouldings are presumed to have been re-used.