All Saints' has an aisled and clerestoreyed nave of four bays with arcades and S aisle windows of c.1300 but Perpendicular windows in the clerestorey and the N aisle. The chancel has a plain 12thc. doorway, and there is another, more elaborate but not much, re-set in the S nave aisle under a Perpendicular porch. A N vestry has been added to the chancel. At the W is a low tower with a bell stage of c.1250-1300. Construction is of irregular stone (aisles and tower) or ashlar (clerestorey and chancel). Included here are the S doorway and the font.

Mears Ashby was held by Countess Judith in 1086, being part of the Earl’s Barton estate held previously by Bondi. No church was noted, and RCHME suggests that no church existed until the estate was fragmented in the 12thc. The earliest notice of it is c.1159, when it was given to Aulnay Abbey. The rectory was confiscated by the king in the Hundred Years War, and in 1392 the church passed to the Carthusians in Coventry.

Benefice of Mears Ashby and Hardwick and Sywell with Overstone.

The font may be related to the re-set W doorway at St Peter’s, Northampton, with which it shares motifs, although the Northampton work does not include the Anglo-Saxon style interlace panels. The visual similarity with Islamic or Mozarabic patterns is surely coincidental. Pevsner simply says, 'Norman, octagonal. With rosettes, interlace, etc. The carving is detailed and so sharp that it appears to be retooled.' The present author accepts that it is retooled, or even scrubbed, and suggests a date in the second half of the 12thc. The S nave doorway is practically identical to those at Upton, except for the head stops.