It is difficult to accurately date the church's foundation or the present building but It is certainly ancient and parts of a moat remain which once enclosed a good five acres including both the church and adjacent East Mersea Hall.
The present church dates from 1250 but had several predecessors.Heritage England has recognised its importance by adding this Grade I church to the At Risk Register.
With a Tudor tower nearly 100ft high, acting as local landmark and navigational aid over the surrounding sea and landscape, the church is at the gateway to the town reached by a single road. The four stage tower features buttresses at the diagonals, traceried panels, blank shields, decorative mouldings, musket ball holes attributed to the Civil War, crenellated parapet and pinnacles, most of which would be lost should the tower collapse.
Inside the building there is a traditional chancel and a wide nave with fixed pews giving a central aisle, two side aisles and a transept aisle. There are Tudor brasses honouring the Beriffe family (1496-1578), an 18th century marble rococo monument (erected 1766) commemorating one of the founders of Lloyd’s marine insurance (Nicholas Magens buried near the high altar), and the 'Tiles of Tragedy' a unique frieze of memorial tiles commemorating local lives lost at sea, started in the 19th century and continuing to the present day. Further maritime connections are evidenced by the arms of the Cinque Ports in a nave window, a reminder that Brightlingsea is the only part of that association north of the Thames. Other items of interest include dummy boards of Biblical figures (only ones outside London) and ten tubular bells, the Baptistry with a Tudor font, and the very ancient west door, used for bridal entry at weddings. The south porch, added in the 16th century, is the main entrance, and is decorated with Tudor fleurons and diadems and spandrels.
Outside in the 7.5 acre churchyard (largest in southern England) there are war graves as well as the gravestones of local people, Horatio Tennyson, the younger brother of the poet, the Victorian philanthropist John Bateman, and Junius Booth, nephew of President Lincoln’s assassinator. With several bird boxes, bug hotels and the chance to see bats, there’s plenty for the environmentalist to appreciate.