St Ethelbert’s comprises a square W tower, chancel, nave and S aisle. The N nave wall of the Norman church survives, although restored. The chancel and S aisle date from about 1300 and the W tower is of the late 15thc. The church, including the porch sheltering the elaborately decorated Romanesque S door, underwent restoration in the 19thc. Within the building there is a Romanesque font and also a colonnette, reused as a support for the Gothic piscina in the chancel.

Larling was in the hundred of Shropham, territory of William of Warenne, at the time of DS. DS records that Hugh held land there. The jurisdiction of Larling was in the royal manor of Buckenham which was thus entitled to financial dues. Before 1066, Ulfketel held land in Larling. The dedication to St Ethelbert, an East Anglian king marytyred in 794, suggests that the church marks the site of an Anglo-Saxon settlement. A decorated 9thc. bone panel was discovered beside it in 1970.

Several of the distinctive motifs decorating the arches and the jambs, combined with the prominent use of the drill, occur on a localised group of portals in the SE of the county. The S doorway is another instance of a Romanesque doorway retained and relocated in a later medieval structure (compare Old Buckenham). The doorway originally stood in the S wall of the Romanesque aisleless nave and must have been dismantled when the old wall was removed on the completion of the Gothic S aisle. The doorway must then have been reassembled several metres to the S in the new aisle wall where an elegant 14th-century stringcourse was designed to accommodate it on the exterior. Was the Romanesque doorway reused for reasons of economy, or taste, or simply out of a sense of respect for antiquity? Perhaps the same tendency lies behind the reuse of the Romanesque colonnette in the 14thc piscina, whose base and abacus could be Gothic versions of Romanesque mouldings. The repertory of sculptural motifs, combined with the decorative use of the drill, place the doorway within a distinctive regional group of carved portals in churches situated mainly in the area between the rivers Yare and Waveney, in the SE of the county. Other sites in this group include Thwaite St. Mary and Chedgrave.

The font is described in Pevsner as 'early 13th-century'. Chamfered angles with simple stop-chamfers can be found elsewhere in the county in a 12thc.context, for example on the internal jambs of the W portal of Norwich Cathedral.