Portsmouth was an obvious target for bombing raids in World War II and civilian air-raid shelters were an obvious requirement. The council took advantage of former chalk quarries on the Portsdown Hills to build two large public shelters.
The one known as London Road was behind what today forms the Cliffdale Gardens Estate. The shelter wase completed at the end of 1941 and accommodated around 2,500 people in three-tier bunks. The shelters included a canteen, medical post, toilets and warden’s post. Today all entrances are back-filled and sealed.