Paddock was built at the start of the 2nd World War on the site of the Post Office Research and Development Station in Dollis Hill, North London. Its purpose was to act as an alternative underground control and command centre for Central Government should a devastating air attack on Whitehall force Government to evacuate central London, as the already built cabinet war rooms would not survive a direct hit. Paddock would provide protected accommodation for the War Cabinet and the Chief of Staff of the air, naval and land forces. Churchill only held one war cabinet on 3rd October 1940, this is because Churchill detested the place and called it 'damp' and a 'useless folly', probably more something to do with the fact the place had nowhere to sleep and no toilets or washing facilities! Here's some pictures of how it looks now:
