W tower of the 14th c., four-bay nave with N and S aisles, square-ended chancel is Norman with 13th c. interior; restored in 1859 by Kirk and Parry. Built of Ancaster stone. On the exterior there is a reset Romanesque corbel table in N and S walls of chancel and a Sheila-na-gig in W wall of W tower. N arcade of the nave is 12thc., but heavily restored in the 1859 renovation. Font is Romanesque.

Ancaster is not mentioned by name in the Domesday Survey, although the neighboring hamlet of West Willoughby, to which it may have belonged, is described as belonging to Roger from Gilbert of Ghent, the Tenant-in-Chief in 1086. There was a church at that date but it may not have been the one in Ancaster.

Corbel tables: The regularity of size and spacing, and crispness of profile, speak to these as not being original as stated by Pevsner and the church guide. Sheila-na-gig: though the location of the figure is low, the chamfering of the join between the W wall of the tower and the SW buttress is echoed in the chamfering of the upper part of the single block of stone from which the sheila has been sculpted, suggesting that she is in her original location. Font: The slender engaged columns of the arcade suggest a date approaching 1200, but the precise spacing of the engaged columns and the unusual treatment of the bases and capitals raise a question about authenticity (compare with font at West Torrington, All Saints).