[Stoka]

Combined Operations, which was responsible for control of the Western Approaches, was moved in 1941 from Plymouth to Derby House, part of Exchange Buildings.

The move was instigated by the fact that German aircraft and U-boats (submarines) were attacking ships travelling to Britain from the French coast, hence, ships were re-directed around the north of Ireland. Western Approaches Command HQ was therefore moved to Liverpool on 7 February 1941.

The complex - which was known locally as the "Citadel" or "Fortress", due to the extensive reinforced-concrete protection given to the basement, which was to become the Operations Room. It was designed to be bomb proof and gas proof, with a 7-foot thick roof and 3-foot thick walls, and 100 rooms covering an area of 50,000 square feet.

The Royal Navy, Air Force and Royal Marines worked jointly there to monitor enemy convoyhttp://img24.imageshack.us/img24/6017/dsc45372909578.jpgs and "wolf packs" of submarines, which threatened to bring Britain to her knees in the early part of the war.

This to me was a miniature version of Hack Green, everything laid out exactly as it should be even down to the very small detail; it even had the musty 'underground' smell. This is well worth the £5 odd entry fee for anyone in the area. Apologies for the crap pics, I forgot to take a tripod and it's superbly dark down there.