Map of West Mersea showing location of Royal Observer Corps observation posts. Some were in place 1938 and it is thought there was a later R.O.C. Monitoring Post in place, thought to be between 1950 and 1964.

Most notes are by Peter Tucker:
Site of Wartime Royal Observer Corp Post in Mersea Avenue
Site of first Observer Corp Post in Yorick Road, pre 1938
ROC Post ? near bottom of Willoughby Avenue. This is perhaps the site that became a WW2 gun emplacement.
ROC Monitoring Unit in line with Empress Avenue in southeast corner of Esplanade Car Park.
Date: 1 July 1998