Old Shoreham located on the east bank of the River Adur, dates back to pre-Roman times. The town and port of New Shoreham was established by the Norman conquerors towards the end of the 11th century.

William the Conqueror had granted Rape (subdivisions) of Sussex, to the de Braose family. The first documentary evidence of St Mary de Haura Church (St Mary of the Haven) was a deed dated 1103, referring to Philip de Braose's return from the First Crusade.

The church had reached its greatest physical extent by about 1225, when this work was completed. The present church is approximately only half the size of the original structure – the former nave was already in ruins by the time of the English Civil War.