London road deep shelter was the second of two deep shelters to be built in Portsmouth, the other being in Wymering chalk pit. Work was started to construct these shelters in late 1941 and by early 1942 they were open. They were designed to hold 2500 people underground with food, sanitation, water, light and places to sleep. At a push the tunnels could hold up to 4000 people. The tunnels were controlled by the shelter warden who had his office near to the main entrance. You could only access the tunnels if you presented a valid ticket or pass. The tunnels also had a small medical facility, a children’s recreation area and was self contained with its own electricity generator.
Construction wise the tunnels are approx 15ft high and about 6ft wide and form an arch of typical metal RSJ and corrugated iron design. There are 3 entrances at the front of the complex, the main entrance and an east and a west emergency exit. There are 2 ventilation shafts in the NW and NE far corners which also double up as emergency exits onto the hill side above. The complex is approx 75ft underground.