The earliest fabric in the church, in the south wall of the nave and in the transept, dates from the late 11th century.

[1] During the 1870s restorations were carried out, including one by the Lancaster architects Paley and Austin in 1876–77, when the seating was increased from 297 to 403.

The tower contains six bells, the heaviest weighing over 10-1-10cwt (525 kg) and being tuned to G major and being cast in 1921.

[8] St Mary's Church was listed at Grade I by English Heritage on 30 August 1966.

It includes Westham village, the hamlets of Hankham and Rickney, an area of coastal development between Pevensey Bay village and the edge of Eastbourne, and a small suburban area of Eastbourne around the former hamlet of Friday Street.