The Cabinet War Rooms were considered as a facility, which would shield the prime minister, his cabinet and the most senior members of the military command in the event of a war. This would enable the government and the military to carry out their functions and counter attacks amidst the chaos.
After 1945 the shelter was no longer needed as the hostile situations had seized to exist by then. Later in 1948 the parliament announced the preservation of The Cabinet War Rooms as a historical site. But its existence was known only by very few until 1981 when Prime Minister, Margaret Thatcher decided the site should be more accessible and thus people were getting aware of its existence.
Another useful website is or www.iwm.org.uk