<P> A military telephone exchange was installed in 1941 and served the underground headquarters . The switchboards were constantly in use and had to have a new tunnel created alongside it to house the batteries and chargers necessary to keep them functioning . The navy used the exchange to enable direct communication with vessels, as well as using it to direct air - sea rescue craft to pick up pilots shot down in the Straits of Dover . </P> <P> Later the tunnels were to be used as a shelter for the Regional Seats of Government in the event of a nuclear attack . This plan was abandoned for various reasons, including the realisation that the chalk of the cliffs would not provide significant protection from radiation, and because of the inconvenient form of the tunnels and their generally poor condition . </P> <P> Tunnel levels are denoted as A - Annexe, B - Bastion, C - Casemate, D - DUMPY and E - Esplanade . Annexe and Casemate levels are open to the public, Bastion is' lost' but investigations continue to gain access, DUMPY (converted from Second World War use to serve as a Regional Seat of Government in event of an atomic war) is closed, as is Esplanade (last used as an air raid shelter in the Second World War). </P> <P> The Annexe level was excavated in 1941 to serve as a medical dressing station for wounded soldiers . It contained two operating theatres and had basic accommodation for patients . Soldiers would be sent for emergency treatment in the tunnels and then transferred to inland hospitals . Within the Annexe level were dormitories, kitchens and mess rooms . </P>

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