The cliché holds that I should begin my article with "It was like the plot to a spy thriller", so I won't.
This is the longest article I have written so far, but I hope you will persevere.
Police broke down the door of Gareth Williams' flat at 36 Alderney Street after he had not been seen for "at least 10 days". Work colleagues had become concerned. At first the story was not heavily-reported, but it soon became clear what "work" this was.
Gareth Williams worked for GCHQ, effectively the UK equivalent of the United States NSA. GCHQ is responsible for SIGINT (signals intelligence) for the British state, i.e. communications interception and the decryption of data collected. The agency has several listening stations, in Britain and abroad in places like Cyprus, and monitors various communications systems.