At least they are going through the Courts or legal procedures in the 21st century; in the 20th GCHQ and the rest of the Government did what they wanted without asking anyone.
The link below is how the govt did it in analogue days (although this installation was officially run by the BBC it was shared by GCHQ and Foreign office; they monitored all the “youth media” of European countries as well as Soviet countries (especially DK, NL, DE, NO, FI who were viewed as having “elements sympathetic to the Soviets”); as well as media of middle east countries.
If local young people asked why it was done the BBC official respone would not be they were “spying” but “we are helping the foreign broadcasters make sure their sound and video is good quality and their signals are strong for Eurovision” 😉 (there was some truth in that but there was of course a surveillance element).
They also listened for pirate broadcasters; and to check other bits of the BBC were complying to the rules. The chaps who worked in there were however decent and would warn me and my mates if our experiments with unlicensed transmitters or anything else was attracting attention before we got ourselves in too much bother or harmed anyone else with interference; and also helped us work legally with community broadcasters. One of them also warned a friend of mine to be careful if you got work experience in radio or TV as the industry was full of creeps..
The equipment there (from 1984) was state of the art for that era and can monitor whole sections of radio frequencies; it also linked to British Telecom via fixed and wireless links and the video/audio could be sent to other places like Cheltenham; although they also had their own similar instalations like this as did the DTI (now Ofcom). The BBC didn’t normally monitor private telecommunicatons (that was GCHQs job) but some of the equipment in those racks could be set up to do either. because it is all “dual use equipment” it is hard to tell exactly what it is being used for.
In the 1980s a lot more data went over the wireless airwaves than through copper cable or fibre optics.
https://www.flickr.com/photos/71155570@N00/sets/72157648015981205
