The church of St Mary and St Radegund adjoins a road junction in the centre of Whitwell village, a short distance from a holy well site. The village is situated in the south-central area of the Isle of Wight in a valley within the southern chalk massif. Whitwell church consists of the chancel, the nave with a S aisle which continues to the S of the chancel to form the chapel of St Mary, a S porch, a vestry to the N of the chancel and a tower which rises above the western end of the aisle. The jambs and the springing of the N side of the chancel arch were retained when the rest of the arch was reconstructed in the early 17thc. The S arcade was originally of three bays and dates from the late 12thc The chapel of St Mary, to the S of the chancel, was widened in the 16thc. The south-western tower also originated at this time, being inserted into the W end of the aisle. The S porch was also added with a cusped image niche above the door indicating a pre-Reformation date (Lloyd and Pevsner 2006, 298-9). The Romanesque features are the northern side of the former chancel arch and the S arcade.

The present church represents the union of two chapels of independent origin. What is now the chancel and nave is dedicated to St Radegund and was founded by the de Estur family of Gatcombe (Hockey 1982, 6-7). Whitwell was endowed so that the rector of Gatcombe should say mass there and maintain the chancel. The smaller St Mary was added to the S side by c. 1200 to serve as a chapel of ease for Godshill parish (Lloyd and Pevsner 2006, 298).

The damage to the W face of the chancel arch includes a slot cut into the fabric. This would seem to be the location of a former rood beam, added to the arch subsequent to its construction. The southern extremity of the S arcade does not terminate in a respond. Instead the arcade continues eastwards for one bay beyond the line of the chancel arch terminating with a respond on the wall projecting between the chancel and the eastwards extension of the S aisle. The arch is round-headed of one order. This arch is supported by a pier which can be dated to c. 1250-1300 (personal communication, Ron Baxter). It would appear that this pier was constructed at the same time as this round-headed arch and that the first bay of the Romanesque arcade was reconstructed with a round-headed arch. Lloyd and Pevsner however say that an arch was inserted between what had been two separate chancels in the 16thc and see the pier as having been reused (Lloyd and Pevsner 2006, 299). The insertion of this pier either in the later 13thc or the 16thc would explain why bay 1 is round-headed whilst bays 2 and 3 are pointed. The arcade of three bays was originally constructed in the later 12thc.