From VJ day 1945 until the collapse of the Warsaw Pact in 1991 the dominant military threat to the United Kingdom was the military forces of the Soviet Bloc. These were therefore, unsurprisingly, the main focus of GCHQ's Sigint efforts; while adequate defence against the perceived current and likely future Sigint capabilities of the USSR was the standard to which CESG –designed Comsec devices, designs and doctrine aspired.
Starting in November 2007 GCHQ has been releasing to The National Archives at Kew copies of its intelligence reports on Soviet Bloc military and paramilitary activities up to 1950 and there are plans to begin release later reports as well. Since 1946 GCHQ has always provided intelligence and Information Assurance support to military, diplomatic and law enforcement Departments of the UK Government and its Allies. (Information Assurance subsumes traditional Comsec and, more recently, Computer Security and secure data handling advice and products.)
One of the enduring legacies of WWII is the Sigint relationship between the UK and the US, to which the Sigint agencies of Canada, Australia and New Zealand have also signed up. Details of the UKUSA Agreement and its development were released to the National Archives in 2009.
With the launch of Communications Satellites starting in the 1960s many communications disappeared from the traditional media of High Frequency (Short Wave) Morse and teleprinter; although neither has disappeared altogether, nor seems likely to. These changes enabled a dramatic reduction, from the 1970s, in the numbers of intercept stations owned or directed by GCHQ, required the opening of some new ones, and result in the much changed appearance and technology of those that remain.
GCHQ made a major breakthrough in the field of secure communications in 1973 when it developed what is now known as public-key encryption and in 1983, GCHQ gained a national profile when its function was avowed to Parliament. In 1984, GCHQ was thrust into the public eye when trade union rights were removed from its staff. In May 1999, the Foreign Secretary announced that he had chosen the site of GCHQ's new accommodation. The two existing sites made way for a single site at Benhall by means of a major new construction project of a design which is well suited to support GCHQ in meeting the challenges the future will bring.