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172 FIGHTING THE ELECTRONIC WAR
eventually produced to assist the newcomers was classified 'Top
Secret Obscene'.8
In 1953 Peter Lunn was chosen to head the vast SIS station
in Berlin, housed in the splendid Olympic Stadium.
Unsurprisingly, he soon decided to repeat his Viennese activities.
This time full Foreign Office clearance was easy to obtain
because of the flow of wonderful material already coming from
Vienna. In contrast to Vienna, the Americans were invited in
at the outset of the Berlin operation. This was partly because
of a desire to share costs, but also because of the existence of
an ideal building close to the Soviet telephone cables, located
in the American sector. 9 The whole operation was a tightly
compartmentalised Anglo-American affair. Few officers in the
huge CIA or SIS stations in Berlin knew of the tunnel's existence,
although back in London a CIA officer was made deputy
head of Section Y, which specifically looked after the tunnel. 10
Berlin was a superb place to collect Soviet comint. Its phone
lines carried communications not only to Moscow, but also
Warsaw and Bucharest. Although the operation was complex,
the underlying hope was that once in place, it might go on
undisturbed for a long time.
SIS agents in the East Berlin Post Office provided maps of
the locations of the cables, and in February 1954 digging began
in earnest. Vitally important was the installation of the taps
themselves, which consisted of heavy metal clips. This involved
freezing the lines to prevent the interference being detected in
the East, a ticklish phase that was again carried out by a special
Dollis Hill Post Office research team. Finally, at the end of
February 1955, the Berlin tunnel was operational. Elaborate
anti-humidity barriers had to be erected to prevent damp
affecting the electronics. The CIA maintained a small local unit
for on-the-spot monitoring of circuits for the protection of the
project and also to provide items of 'hot' intelligence for Berlin. 11
The overall 'take' from the Berlin tunnel was vast, and far
exceeded the capacity of any local monitoring. Some twentyeight
telegraphic circuits and 121 voice circuits were being moni-