Thanks! I just read about these. Speaking of The Big One, and considering Christian's post above, we would have to include Gold Seal Notes as examples. They were paid out to troops in North Africa, because they were not used in the USA.
Thanks. It is Liza Mundy and my neighborhood Barnes and Noble has three editions in stock. I will pick it up tomorrow. Thanks! I was exchanging emails with Kerry Howard, an author in the UK working on this book, but it seems stalled. Howard did come out with a book about Margaret Rock. Dear Code Breaker: The Letters of Margaret Rock (Bletchley Park Code Breaker & John Rock (Parachute & Glider Forces Pioneer). 2013.
During the Hungarian War of Independence (1848-1849) secret messages were passed inside of specially prepared revolution coinage (screw types). The coin most often used for this purpose was the 1849NB 3 Krajczár (KM-434) due to its size. The coin is Copper 32.5mm and 4mm thick.