During World War Two, many radio hams in the UK were recruited to a special unit called the Radio Security Service (RSS) to intercept and analyze messages between German agents who had infiltrated the UK, and their masters in Germany.
The hams provided their own radio equipment, and used Morse code skills to copy down messages.
Later they moved to Arkley View, a large house north of London, where they were put in uniform as part of the Royal Corps of Signals, but their duties were somewhat informal.
They would process logs from volunteer interceptors and other radio operators, classifying and cross-referencing them where appropriate, to build up a picture of the German agents’ communications.
Many of the agents were identified, and some were turned into double agents.
By the outbreak of peace, the RSS had decoded around a quarter of a million intercepts.
