The church comprises chancel, crossing tower, N and S transepts, and nave. The nave has N and S aisles, S porch, and clerestorey. The crossing survives from the original 12thc. cruciform church. The original transepts were rebuilt in the late 13thc. as was the chancel. The nave arcades are early 14thc. Much of the exterior has been rendered, with the exception of the tower and transepts which have rubble walls. The transept walls are coursed. The church was restored by William Butterfield in 1869-72.

DS does not mention a priest at Anstey. The advowson appears to have descended with the manor. In the late 17thc. it was sold to the Masters and Fellows of Christ's College, Cambridge, who still hold it.

Pevsner compares the shaft rings in the E and W crossing arches to those found in the (reset) slype arcading from St Albans Cathedral, but feels that those at Anstey are later in date, perhaps as late as c.1200. Thurlby also makes a similar comparison. The Anstey mouldings are however less formalised and more idiosyncratic than the St Albans bobbin mouldings. Thurlby also compares the acanthus leaves on the Anstey arch with the St Albans carvings, although the St Albans carvings are considerably more refined and developed.

The font, although with Romanesque features, must be very late 12thc. or early 13thc. judging by the style of the figure carving. Bond suggests 13thc.

A font of the same type is found in the the church of St Peter, Cambridge.