Located at the end of the Grande Jetty near the outer port, Wn07 featured a small pillbox building which not only had embrasures for a machine gun but was also a crucial building for the defence of the port.
This is the building in which the pre-positioned mines and depth charges located on the seaward side of the harbour wall could be triggered in case of a seaborne or underwater attack was detected.
In front of the pillbox an anti-torpedo net was positioned, stretching across to the east jetty to prevent attacks on the ships using thew outer dock area.