It is said that there was a small priory near the church, probably to the west, which is known to have been established in 1046.<1><2><3>

Little is known of the history of the priory. Mersea was granted to the abbey of St. Ouen at Rouen by Edward the Confessor; the date of the grant, according to a doubtful charter given by Morant, being 1046. It was therefore the oldest of the Essex religious houses with the exception of Barking. In 1294 a valuation of the priory details the extents of the three manors belonging to it (Mersea, Peet and Fingringhoe). It was stated that two monks dwelt there. The priory also owned the churches of West Mersea and Fingringhoe. See 'Alien houses: West Mersea', in A History of the County of Essex: Volume 2, ed. William Page and J Horace Round (London, 1907), pp. 196-197. British History Online http://www.british-history.ac.uk/vch/essex/vol2/pp196-197 [accessed 25 July 2016].

The County Series at 1:2500 scale Epoch 1a (1874-87) has 'Benedictine Priory (Site of)' marked to the west of the church, to the north of Coast Road and close to Yew Tree House. However, there does not appear to be any physical evidence of the priory.

A test pit (Test Pit 1) excavated by Access Cambridge Archaeology in 2006 in the garden of Yew Tree House, High Street, produced a small number of sherds dating to the medieval and post medieval periods. The test pit also produced three sherds of Roman pottery, a fragment of Roman box-flue tile and two small tesserae.<4>