The parish of Aldeby lies in the extreme southeast of Norfolk, forming a stretch of the border, here formed by the River Waveney, with neighbouring Suffolk. Aldeby is located roughly 3 miles northeast of the Suffolk market town of Beccles and sits in lanes just over 2 miles east of the A143 road which links Beccles with Great Yarmouth. Aldeby sits upon a peninsula of Norfolk which pokes into adjacent Suffolk, a peninsula formed between the arms of a large meander of the river Waveney. Aldeby would have utilised both the water-meadows bordering the river as well as the more dry land slightly higher to give it a more varied farming regime than is typical of either of the two counties. The water-meadows providing rich grazing whilst the dry sandy soils were ideal for arable crops, notably cereals. Aldeby is a slightly dispersed settlement, a concentration of properties along St Mary's Road aside, it is a scatter of farms and cottages across a wide area, indeed Aldeby parish was rather large by eastern Norfolk standards, covering just over 3,000 acres it was almost twice the size of most Broadland parishes.

St Mary's church sits on the eastern side of St Mary's Road almost on the edge of the lower ground fronting the Waveney. The church has a long history having been founded as one of 5 priory churches in the county in or around 1100. The least important of the 5 it supported merely a prior and 4 monks in husbandry. The priory was, of course, a victim of Henry VIII's suppression of the monasteries. The church, however, retains something of that early origin being formed upon the cruciform design favoured by the Normans, the western doorway is an elaborate work of the 12th century Norman Romanesque period. Lancet style windows in the nave and the nature of the tower's bell-opening are also sufficient for Pevsner to assign a Norman date although the tower was largely rebuilt in 1633. The northern transept, a peculiarly long piece, shows both 12th century Norman and 13th century Early English Gothic features, albeit much restored, whilst other windows are from the early 14th century. Much of the main body was thus complete by or about 1320. The usual Victorian restoration, in this case, was of 1880 and as Pevsner much bemoans was thorough resulting in a church he describes as "over-restored". Whilst St Mary's Road is quite narrow there is a broad verge for parking at the northern edge of the site allowing an extended visit, the churchyard is open & uncluttered with no obstacles for the photographer.