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268 SPACE, SPY SHIPS AND SCANDALS
the l:leginning of the Nimrod Rl programme. 33 This new equipment
revealed the ever-increasing complexity of sigint. The
existing Comet aircraft depended on teams of human operators
wearing headphones who undertook the reception and analysis
manually, using narrow-band receivers. However, the growing
density and complexity of electronic signals meant that they
were simply being overwhelmed. It was 'impossible for the
operator to sort out and examine all the active transmissions'
in the limited time that an aircraft spent over the search area.
This meant that the most interesting materiaL the unusual
signals that might mean new enemy equipment, was being lost.
Plessey's new system was designed to do much of the work of
the operator, and store what it detected for leisurely analysis
after the aircraft had returned from its mission. 34
The key decisions on the Nimrod were taken in March 1964
by the London Signals Intelligence Committee, which oversaw
all of British sigint. It agreed that although the cost of replacing
the Comets 'represents a significant proportion of the UK expenditure
on Sigint', it was nevertheless essential. It was not just
that some signals were otherwise inaccessible, but also that problems
over bases meant a continual reduction in ground stations
in areas such as Africa, causing GCHQ 'the greatest difficulty'.
The committee noted that stations in Iran and Turkey, which
were the source of much intelligence on new Soviet radars,
'could be denied to us' at any time, adding 'this had already
nearly happened in Turkey'. It then compared the costs of
possible aircraft, including the Boeing 707, but the Nimrod Rl,
which was a specialist variant of the RAP's maritime patrol
aircraft, was by far the cheapest. 35
The Nimrod had strong backing from the Chiefs of Stafp6 It
bolstered the much-prized special Anglo-American intelligence
relationship by making a bigger contribution to shared sigint. 37 As
Air Vice Marshal Harold Maguire, the Deputy Chief of Defence
Staff for Intelligence, explained, there was a limited choice of partners
to share burdens with, for although the French ran airborne
elint missions, there was no exchange with them. Other NATO