Sending a Message: What was MI6 Doing With All That Semen?

When people think of MI6, they tend to think of suave spies gliding across the scene, armed with a range of gadgets to disarm the enemy. They tend not to think of any of those gadgets involving bodily fluids.

However, one of the earliest forms of secret messages was to use semen as invisible ink. But how did this come to be? Well, this article will give you some idea behind the thinking of the semen ink pen and why it was, worryingly, not as successful as its creator may have hoped.