The church has an aisled nave with a clerestorey and N and S porches, a very tall W tower of five storeys with angle buttresses and a spire supported by flying buttresses. The chancel has the Watts funerary chapel on its N side, with a crypt below, and E of the chapel is a vestry formed by enclosing the remainder of the N chancel wall. The 12thc chancel is a remarkable survival. In addition to the Norman chancel arch, its exterior side walls divided into five bays by half-columns with capitals at the level of a finely carved corbel table with heads, and the bays themselves formed a giant order arcade. This survives on the S side (along with a fine priest's doorway), and in the 2 bays of the vestry on the N. There is a 12thc piscina in the S wall of the vestry. For the rest, the nave aisles are 13thc, but the clerestory and arcades were rebuilt later, in the 14thc and 15thc. The tower was built in 1409, but rebuilt after its spire was struck by lightning in 1804.

Edward the Confessor's housecarl Alden held Hanslop before the Conquest, and in 1086 it was held by Winemar the Fleming and assessed at 10 hides. Winemar's lands passed at his death to Michael de Hanslope, and when he died the Honour of Hanslope and the manor passed to William Mauduit, married to Hanslope's daughter Maud. The manor largely remained in the possession of the Mauduits until 1215, when Robert Mauduit joined the wrong side in the war against King John. The manor was eventually returned to Robert and passed to his son William , whose own son, also William succeeded to the earldom of Warwick through his mother. Hanslope remained in this line throughout the medieval period.

The church was originally a chapel of Castle Thorpe, but following the grant of a licence by Bishop Grosseteste the positions were reversed. Advowson passed with the manor until 1522, when it was granted by the crown to the Dean and canons of Newark College, Leicester.

The giant order respond capitals of the S wall arcade are totally unconvincing as 12thc work but clearly copy and adapt forms found on the chancel arch capitals, and might be of interest to students of the Romanesque revival. Pevsner and Williamson (1994), 369 note the round-headed chancel windows, which are neo-Romanesque and are compared with work of the 1790s at Tickencote (Rutland). They make no mention of the piscina.