A former nuclear bunker converted into a cannabis factory was uncovered in a night-time raid in a south-west England village, British police said Thursday.Six people were arrested after the bust late Wednesday in Chilmark, Wiltshire, at an underground shelter built in the 1980s to protect government officials and local dignitaries in the event of a nuclearattack.Police staked out the impenetrable former Ministry of Defense site, waiting for suspects to emerge.Officers then used the suspects' keys to gain entry as they knew they would never be able to get through the nuclear blast doors.Three men were detained outside the bunker and arrested on suspicion of cannabis production, while three more men, believed to be operating as gardeners, were found inside and arrested on suspicionof cannabis production.Detective Inspector Paul Franklin called the set-up "enormous," with almost all of the approximately 20 rooms on two floors, each 60 meters long and 21 meters wide, used to grow marijuana plants.Franklin said thousands of plants were in the building and estimated the value of the crop at 1 million pounds (1.2 million dollars).