ANTI TANK VERTICAL RAIL.
.Shore end of the north pier.
WW2 tank road block,consisting of 12 squar sockets in the surface of the pier. These sockets have since been concreted over, but in wartime would of been fitted with plugs, which in the event of invasion would of been removed and steel girders slotted vertically into the holes to impede progress of tanks and other vehicles.
There are two others, one located on the south pier and the other on the old pier.