At the outbreak of World War II , the island became part of the front line for invasion and was heavily fortified . Along with other coastal resorts , the island drew in evacuees from London , though as the war progressed , these were moved to safer settlements further inland . 2000 troops were stationed on the island to guard against invasion . A battery of 4.7 inch guns was installed along the beach along with a Battery Observation post and a number of searchlights and pillboxes . Several of these installations survived and can still be seen along the south coast of the island , one of which has been converted into a cafe . After the war , the island suffered from severe winter weather in 1947 which destroyed much of the oyster fishery , and from the flooding of 1953 , where numerous beach huts were swept out to sea
flooding of 1953
North Sea flood of 1953
Mersea Island