The church is of standard Cornish aisled type, a S arcade of polyphant and a slightly late N arcade of granite. Nothing remains from the Romanesque church except the font.

In the Domesday Book Launcells is written Landseu in error for Landsell, probably Lancellys - the church of Cellys - indicating the presence of a Celtic monastery on the site and perhaps the same name as Lansallos. Although secularized in the Conquest, by 1261 it was appropriated to the Abbey of Hartland in Devon, which received the great tithe of the parish at Forrabury. As it did at Launcells, this abbey possibly began to gain influence in the Norman period; and Matilda of Launcell granted all her wood in Launcell manor to Hugo, abbot of Hartland, in King John's reign (1199-1216). In 1382, a dispute between the vicar and the abbey, concerning who should pay to repair or rebuild the old chancel, was settled by the Bishop of Exeter.

In Sedding's day the font stood adjacent to a pier of the N arcade, and was nearly enclosed by old woodwork. Henderson considered it to be one of the earliest Norman examples, "probably fashioned by Saxon masons"; it could also be seen as very rustic version of the font at St Stephen's by Launceston. Date: last quarter 11thc.