'At the end of WWII, contrary to what one might believe, the use of
Enigma did not case in a bunker in Berlin in 1945. It lingered on to
an insignificant demise in 1955. The East Germans continued to use the
Enigma equipment, but its role diminished, until by the early 1950s
they were using it only in Berlin.
'Case notations were used to identify discrete communications entities
so that one could follow and maintain continuity on a given set of
communications. These designators were assigned according to a
prescribed system. For instance, in GCPB 00101, the GC denoted East
German, The P indicated Police, and the B meant that the mode of
communications was Manual Morse. The 001 and 01 signify the number of
the network and the net within the network. In this case we have only
one net and that was the East German police in Berlin. GCPB 00101 was
the last communications network to carry Enigma traffic, which the
U.S. exploited.
'The content of the communications carried on GCPB 00101 could be
described as mundane at best. It contained fire damage reports, state
of readiness of various fire stations and police reports, mostly
regarding insignificant arrests. This was not the exciting content
produced during WWII, yet the priority to intercepting this traffic
was extremely high. People working in the traffic analytic aspects of
the problems and those continuing the efforts to read the message
could not understand why the mundane content of the messages would
warrant the high priority afforded this target in the
mid-1950s. Obviously those in the hierarchy at that time knew, but the
rest could only speculate.
'In retrospect it would appear that, with the famous Berlin Tunnel
operation under way, the U.S. was most interested in knowing about any
reflection or knowledge on the part of East German of the tunnel′s
construction and activities. Police and fire reports might just
provide such information and hence the high priority given to
GCPB 00101. Little did we know at that time that the noted British
traitor, George Blake from MI-6, in all probability had already had
compromised the tunnel operation.'