It is the strangest place, the demilitarised zone (DMZ) that separates South Korea from North Korea. It is simultaneously a historic battlefield, a sombre graveyard, a tourist honeypot full of coach parties from Seoul, and a Cold War frontier, hotly defended on either side. One minute you are looking at a kiddies’ funfair, or a shop that sells ‘souvenir North Korean money’, the next you are staring at endless barbed wire and monuments to failed North Korean defectors, shot dead as they attempted to cross the two-and-a-half-mile strip of landmines.