The church has chancel, nave with N and S aisles and W tower. The tower is substantially late 11thc. to early 12thc. and is wider than the nave. It has a plain segmental-headed W doorway, which may be of later date and a plain round-headed arch to the nave. The plain chancel arch and part of the chancel walls are 12thc. Two of the three bays of the N and S nave arcades are 13thc. and the remaining bay is of 1861. The chancel is of 1862-3 by G.G. Scott. Simple late 11th to early 12thc. sculpture is found on the bell-openings.

The Domesday Survey does not mention a church at Clapham, but records that Miles Crispin held the manor. It also records that Ramsey Abbey (Huntingdonshire) asserted their rights to the manor as they had held it prior to the Conquest. VCH notes that Clapham had been granted to Ramsey Abbey by William I in 1078 and that it had been held of the Abbey by Britric (for life only according to the Abbots). It was then passed to Robert D'Oilly and then to Miles Crispin and does not appear to have reverted to Ramsey Abbey .

The church was originally a chapel and was attached to Oakley Church (Bedfordshire) and, with Oakley, held by Caldwell Priory (Bedfordshire) until the Dissolution.

VCH records that the entire church apart from the tower was rebuilt in 1861.

Until relatively recently the tower at Clapham was thought to be pre-Conquest with a later top stage, but it has been demonstrated that the tower is in fact of one campaign and, taking into account the carvings on the bell-openings which include early voluted capitals, the entire structure cannot be earlier than the late 11thc. (Fernie, 2000).