The UK spy agency MI6 experimented with using semen as invisible ink; presumably because this fluid was readily available to several of their field agents on a few moments’ notice. The agent in charge of the project? Mansfield Cumming. This and other revelations appear in MI6: The History of the Secret Intelligence Service 1909-1949, to be published this week.
A member of staff close to “C”, Frank Stagg, said that he would never forget his bosses’ delight when the Deputy Chief Censor said one day that one of his staff had found out that “semen would not react to iodine vapour”.
Stagg noted that “we thought we had solved a great problem”.
However, the discovery also led to some further problems, with the agent who had identified the novel use having to be moved from his department after becoming the butt of jokes.
MI6 ‘used bodily fluids as invisible ink’
(via Super Punch)
(Image: Invisible ink, a Creative Commons Attribution (2.0) image from superfantastic’s photostream)