* This Monopoly story has assumed the tinge of myth and James Bond about it, but its ingenuity was certainly typical of MI9 and its American equivalent MIS-X. The key item in this mystery is a letter from an M19 agent, Captain Clayton Hutton, to Norman Watson, an executive at John Waddington, sent at the end of March 1941. It states: ‘I shall be glad if you shall make me up games on the lines discussed today containing the maps as follows: One game must contain Norway, Sweden and Germany. One game must contain N France, Germany and frontiers. One game must contain Italy. I am also sending you a packet of small metal instruments. I should be glad if in each game you could manage to secrete one of these.’

There is no specific mention of Monopoly, but another letter refers to Free Parking (the space on the Monopoly board had been marked with a full stop to show that there was a map inside).

Monopoly had already annoyed the Germans before the war. Goebbels objected to the fact that the most expensive area on its Berlin board was Insel Schwanenwerder, where many Nazi leaders lived. Fearing that the Third Reich would be associated with capitalism and extravagance, the manufacturers Schmidt were advised to stop selling it; an allied bombing raid on the company subsequently destroyed any remaining copies. But the game is back in business in Germany, with Unification transforming the layout.