A security guard at a Las Vegas casino, he was approached by a former colleague who told him about this great job out in the desert, with double the money and a lot less stress than frogmarching drunks out of bars. All he would have to do was sit in a small guard hut, either at one of the many checkpoints at the heart of the base or on the two dirt roads that cross its perimeter, and make sure that whoever came through had the relevant pass. He’d be paid $17 an hour.

By now, Groom was a significantly-sized airbase, with numerous permanent buildings staffed by employees of the US Air Force, the CIA and a raft of defence contractors. Occasionally there’d be an accident, and security would have to rush to the aid of a downed pilot. High spirits – especially after long, late-night sessions in Sam’s Place, the on-site watering hole – might occasionally call for a security presence to calm people down. Once or twice Dunham and his colleagues had to escort uncleared personnel off the site when a test flight was rescheduled. And every week, Dunham and his colleagues had to supervise the burn…