Editing MI8 (section)

===MI6 takeover===
RSS had in effect become the civilian counterpart of the military's "Y Service" intercept network.  By mid-1941, up to 10,000 logs (message sheets) a day were being sent to Arkley, then forwarded to the code-breaking centre at [[Bletchley Park]].

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. There was brief conflict over who would control it.  In the end, it became the communication and interception service of [[Directorate of Military Intelligence (United Kingdom)#Sections|Military Intelligence, Section 6]] ([[Secret Intelligence Service|MI6]]). Previously, MI6 had possessed no such capability.

The new controller of RSS was Lieutenant-Colonel E.F. Maltby. From 1942, Lt. Col. [[Kenneth Morton Evans]] was appointed Deputy Controller.  Roland Keen, author of ''Wireless Direction Finding'', was the officer in charge of engineering. The service was well-financed. It was equipped with a new central radio station at [[Hanslope Park]] in Buckinghamshire (designated Special Communications Unit No.3 or SCU3).  The Abwehr was now monitored around the clock. 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 machine|Enigma]] cypher, giving enormous insight into German intelligence operations.

At its peak in 1943-1944, RSS employed - apart from VIs - more than 1,500 personnel, most of whom had been amateur radio operators.  Over half of these worked as interceptors while a further number investigated the numerous enemy radio networks.  This revealed important information, even when it was not possible to decode messages.<ref>Abrutat 2019, pp. 51-52</ref> Few transmissions by secret agents of German Intelligence evaded RSS' notice. Changes in procedure, which the Germans used for security, were in many cases identified before the enemy had become familiar with them.

Following the end of the war, RSS HQ moved to Eastcote and was absorbed by the [[Government Communications Headquarters]] (GCHQ).