8,548. [He alleges] an underground base at a place called Peasemore. Essentially there are no access points visible at that base. They’re all several miles away at other bases. You’ve got Harwell which is about ten miles north of Peasemore, which is a base that we know of that has underground facilities, there’s Greenham Common that you mentioned, there’s another one Welford to the south-west; to the north-west you’ve got Watchfield ... Rudloe Manor which is a base west of those bases is connected by some kind of underground tunnel to Boscombe Down which is connected to Porton Down ... (Alien & Underground Base) ibid.
8,549. Here’s a summary of likely locations of extraterrestrial underground bases around the world: Alaska, the north Pacific, New Mexico, West Virginia, Puerto Rico, the Gulf of Mexico, Costa Rica, Bolivia, the Uruguayan coast, the mid Pacific, Australia, Antarctic, Soviet Union. (Alien & Underground Base & Extra-terrestrial) ibid.