1941, eh? Britain had great success in cracking German (and other) codes early in the war, as did the US with Japanese code systems. It shouldn't be surprising that the paranoia of the times would lead radio monitors to suspect cryptic messages almost anywhere, or everywhere. The level of suspicion was probably heightened as regarded the Republic of Ireland because of its official neutrality in the war. In such times, the notion of 'you're either with us or agin us' becomes prevalent and the very idea of principled neutrality can be seen as a guise to benefit "the other side." A good look at code-breaking in WW II can be found in Robt. Stinnett's "Day of Deceit", published late last year.