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376 INTO THE THATCHER ERA
GCHQ, he had been canny. Prior to his resignation he had had
the foresight to take copies of five hundred secret documents,
which he was then able to hand over in segments. On 16 May
1980 he delivered fifteen reels of film to the KGB in Vienna,
for which he was paid £600. More than a year later, on 16
November 1981, he travelled to East Berlin, where his stock of
espionage equipment was replenished. He still refused to rejoin
GCHQ, but now handed over his last haul of stored material.
This was top-grade stuff, signified by the fact that he now
received £4,000 from the delighted Soviets. The head of GCHQ's
Security Division would later conclude that while all of Prime's
espionage was 'very grave', the 'most damaging of all' was the
material he handed over in Berlin in 1981. 27
Britain's security authorities have always maintained that
'The damage inflicted by Prime was of a very high order. '28 NSA
has concurred, concluding that 'Prime's case was of major importance
for cryptology.'29 What exactly had he handed over to his
KGB masters When he moved from London to GCHQ
Cheltenham he had become a Higher Linguist in J Division,
and was given a 'Byeman' clearance to work on material from
the new American sigint satellites. The key satellites were codenamed
'Ryolite' and 'Canyon', and had first been launched in
1969. They had been designed primarily to pick up Soviet missile
launches and collect telemetry from missiles, which the Soviets
were not bothering to encrypt. Surprisingly, they also proved
capable of collecting huge amounts of communications in the
VHF and UHF wavebands that were spilling into space, and
microwave telephone traffic. Space was an undiscovered sigint
goldmine. By the mid-1970s there were more than a dozen of
these satellites in orbit, producing a fantastic amount of intelligence
on Russia, China, Vietnam and the Middle East, much
of it from telephone calls. Because the 'take' was so enormous,
NSA had been forced to ask its UKUSA allies to help process it.
It was for this reason that Prime was pressed into service on
'Canyon' intercepts. 3o
Prime's material dovetailed nicely with intelligence provided