Before leaving for missions, British airmen were told that if they were captured, they should look for escape maps and kits in Monopoly boards and other games delivered by charity groups. They were told that "special edition" Monopoly sets would be marked with a red dot on the free parking space.
Watson said that in addition to the concealed compass, tools and maps, real bank notes were hidden under the fake money.
During the war, the Official Secrets Act prevented anyone involved from disclosing the plan, and Watson said his father was concerned that the company could be targeted by the Germans if they were tipped off
"It was very special and very secretive," Watson said, adding that he didn't learn about the company's role helping the military until years later.
Waddington printed six different maps that corresponded with regions surrounding six different German camps, Orbanes said. Monopoly kits bound for a camp in Italy, for example, would include a map of Italy and Italian currency (lira).
To make sure each set reached its destination, the secret service devised another code.
"Each game was pinpointed as to the camp it would go to," Orbanes said. To innocuously tag each board game, a period was added after different locations on the board.
A period after "Mayfair," for example, meant that the game was intended for Norway, Sweden and Germany. And a period after Marylebone Station meant it was a game destined for Italy. (It being a British version of game, London streets replaced the Atlantic City streets used in the original American version.)
While "Mr. A." may have been responsible for bringing the war to Waddington's door, map experts credit another MI9 officer, Christopher Clayton Hutton, with hatching the master plan.
"He put two and two together," Hall said, adding that Hutton was likely not alone in implementing it. "He was the first who had this idea to get maps into camps concealed in board games. It looks innocent, they wouldn't arouse any suspicion... it just looked like someone was being charitable."
Hall and others familiar with the Monopoly maps say not wanting to compromise the integrity of the Red Cross, the secret service created fake charity groups to smuggle the games into the German camps.
Barbara Bond, Pro-Chancellor at the U.K.'s University of Plymouth who is writing a book on silk maps, said Monopoly games weren't the only vehicles used to conceal escape maps. Decks of cards, the board game Snakes and Ladders and pencils also concealed maps for prisoners.
"There was a whole industry going on," she said.
During the war, hundreds of thousands of silk maps were used to help prisoners escape. And she said it marked a change in the way the military viewed POWs.
During World War I, she said, "If you were captured in battle that was it."
But after Winston Churchill and others shared their experiences as POWs, she said, the perception of them changed.
"The POWs could still do a job," Bond said. "Not only was it their duty to fight if they were captured, it was their duty to escape."
The silk (and rayon) maps and the clever ways they were distributed, she said, reflected that philosophy.
Though silk maps from that era exist in libraries, homes and museums around the world, none of the original rigged Monopoly sets still remain.