MI8
During World War I MI8 officers were posted to the cable terminals at Poldhu Point and Mullion in Cornwall and Clifden in County Galway, continued until 1917 when the work was taken over by the Admiralty.
The Radio Security Service evolved from the Illicit Wireless Intercept Organisation (IWIO), which was given the designation MI1g and run by Lt Col. J S Yule.
[1] Col Yule also made detailed plans for similar networks in British overseas territories, before IWIO evolved into RSS in September 1939.
But Lt Col Adrian Simpson developed a proposal which stated that a small number of stations, located around Britain, would not work.
At the start of World War II, Vernon Kell, the head of MI5, introduced a contingency plan to deal with the problem of illicit radio transmissions.
His brief was to "intercept, locate and close down illicit wireless stations operated either by enemy agents in Great Britain or by other persons not being licensed to do so under Defence Regulations, 1939".
Working from cells at HM Prison Wormwood Scrubs, Worlledge selected Majors Sclater and Cole-Adams as his assistants, and E.W.B.
Gill had been engaged in wireless interception in World War I and decided that the best course of action would be to find the transmissions of the agent control stations in Germany.
Working alongside them, at Wormwood Scrubs, was John Masterman, who ran MI5's double agent XX program.
RSS assigned the task of developing a comprehensive listening organization to Ralph Mansfield, 4th Baron Sandhurst.
RSS also established a series of Radio Direction Finding stations, in the far corners of the British Isles, to identify the locations of the intercepted transmissions.
In May 1941, RSS's success and the fact that some of its personnel had managed to decode some Abwehr cyphers ahead of Bletchley, caused control of the organization to be transferred.
It was equipped with a new central radio station at Hanslope Park in Buckinghamshire (designated Special Communications Unit No.3 or SCU3).
The volume and regularity of the obtained material, enabled Bletchley to achieve one of its great triumphs in December 1941, when it decoded the Abwehr's Enigma cypher, giving enormous insight into German intelligence operations.
