It continued as the Government Communications Headquarters (GCHQ), focusing on the USSR and its socialist allies.
In conjunction with the US National Security Agency it played a significant espionage role in the Cold War.
New "terrorist enemies" have since been created.
In addition to maintaining surveillance of eastern Europe, GCHQ supports the US's global hegemonic aspirations by targeting the Middle East and north Africa.
It has acknowledged it gathers intelligence to identify targets for drones in Afghanistan.
Anne Lee
Otley