Geograph - photograph every grid square

When I saw this on the map, I was rather surprised because it is several hundred metres from the sea in the middle of a forest. However the 1903 edition of the Ordnance Survey six-inch map Link shows that when it was built in the second half of the 19th century the beach was much closer than it is now, and of course the forest was not planted until the middle of the 20th century. It was probably used during the Second World War in conjunction with the military camp and emplacements just to the north.