St Margaret's has an aisleless nave with a blocked N doorway and a porch protecting the S doorway; a chancel with a long S chapel under a separate roof and a W tower. The N doorway indicates that the nave is 12thc., and the S doorway is a 13thc. modification. The brick and flint porch is 16thc. The chancel and its chapel are 14thc. Both E windows are Perpendicular, but of different dates. The E wall has been mortar rendered and inappropriate barge-boards added. To the N of the chancel is a lean-to of brick, roofed with the chancel. The W tower is Perpendicular, with diagonal buttresses and flushwork panels on the plinth. Construction is of flint with ashlar dressings. The only Romanesque sculpture is on the blocked N doorway.

The Domesday Survey records two holdings in Somerton. The first was given by William I to the abbot and monks of Bury St Edmund's; the other was held by Starcher under 'the glorious King Edward' as a manor, and was held by Roger from Robert fitzCorbucion in 1086. Both were small, and neither included a church or a priest.

Glem Valley United Benefice, i.e. Glemsford, Hartest with Boxted, Somerton and Stanstead.