James Bond's Invisible Ink: Semen!?

A new book which documents the history of the Secret Intelligence Service (SIS) from 1909-1949. Author Professor Keith Jeffery was given unparalleled access to MI6 archives to research the book on the famously secretive organization.
One document from 1915 said Mansfield Cumming, the first chief of the SIS, had been trying to find a good invisible ink, before adding: "Heard from C that the best invisible ink is semen."
Come to think of it, this could explain why there is always beautiful women staying with James Bond as he might have to write reports to his boss the morning after using invisible ink... So I wonder why he needs also a special pen for that application!

HK Snob