The rise of GCHQ can most definitely be pinned to the rise in electronic communication. Signals Intelligence (SIGINT) by its very nature needs signals from which it can draw its intelligence. These signals in the 1950’s were relatively simple. “Communications structures before the internet can be thought of as fixed networks in which any ‘message’ (telephone call, fax, or data transmission) travelled over a single identifiable path between two communicators.” (taken from http://www.guardianpublic.co.uk/gchq-transformation-pepper-management) They stayed this way for the whole of the cold war, finally being usurped by the internet and the knowledge revolution that this has bought about. This made interception of communication by GCHQ relatively simple. Furthermore, the target of its efforts from the end of World War Two was also very simple. Russia and the Soviet Bloc. The largest military threat to Great Britain, until its collapse in the 1990’s. One target, simple interception. Easy.
Britain in the 1950’s just about had hold of its empire and so had listening stations around the world. The American’s due to the special relationship could piggy back off these too. They were territory short, but technology rich. The special relationship, was and is one of necessity rather than warm chumminess. This of course changed as British power dwindled in the post war years, but key British stations, such as Hong Kong and Cyprus, kept the relationship solid for the rest of the twentieth century and in to the twenty first.
At home, GCHQ actually became GCHQ in the post war period. It moved its main operations from Bletchley Park to Eastcote in Middlesex in1946 and then to Cheltenham in the 1950’s. Then relatively speaking GCHQ kept its head down and out of the spotlight. Whilst failures in other services, such as the scandal around Kim Philby, were being reported, there is little if any reporting regarding GCHQ. MI5 and MI6 were portrayed in book form by Ian Fleming and John Le Carre, portrayed in films by Sean Connery and radio by Sir Alec Guinness, but no glamourisation of GCHQ ever appeared. But then I guess the intercepting of radio transmissions or tapping telephones is less enigmatic to a reader or viewer than the personal relationships involved in human intelligence operations. (HUMINT).
This period was not all sunshine for GCHQ and by association the NSA. They completely missed the date of the first test of Russia’s burgeoning nuclear capability, the invasion of the Falkland Islands and the collapse of the Soviet Union. Proving that even the ability to hear everything, still involves some element of knowing what you’re listening for.
Minor scandal in the late 1970’s revolving around the journalist Duncan Campbell and the ABC Trial, followed up the Geoffrey Prime affair. Possibly the biggest fail of UK intelligence since the Cambridge five, began to bring the work of the service to light. This was not helped by Margaret Thatcher doing what she did best. Attacking unionisation, this time inside GCHQ. All told the work of the organisation was bought to light and with scrutiny on spending at the end of the cold war, GCHQ was becoming firmly implanted in the common psyche.