Minewatching observation post established on the end of Bell Wharf on the northern extremity of Swanscombe Marshes during the Second World War, one of a network of such posts at 600 yard intervals along the bank of the river Thames to spot for the landing of air-dropped anti-shipping mines. Of unknown design, it probably originated in 1940 to be decommissioned by 1945. The end of the pier was demolished c. 2000. (location accurate to the nearest 10m based on available information)