An exhausting mixture of boredom and concentration

The wartime code-breaking successes of Bletchley Park are deservedly well known.  The story of how they decrypted German and Japanese codes, most famously the Enigma, has been the subject of histories, novels and films, so much so that Bletchley is glamour. Much less well known, however, and much less glamorous — rarely even thought about — is the story of how those clever cryptologists got the coded radio signals they worked on. Where did their daily and nightly fodder come from?  It certainly wasn’t from sticking an aerial in the attic and waiting to see what came out of it.

The signals Bletchley decoded came from the Y Service (Y for wireless, a useful wartime confusion), a worldwide network of listening stations manned mostly by very young men and women who manually transcribed enemy signals and sent them back to Bletchley. Many were still in their teens, having been recruited via IQ and aptitude tests from schools, the armed forces and the ranks of amateur radio enthusiasts.