Körner, "The Pleasures of Counting" (1996), has a bit in "The Poles" (on breaking Enigma) that might shed some light on traditional tradecraft vs mass surveillance. (compare what the Stasi could accomplish with their non-automated labour-intensive methods)
> Churchill's romantic soul loved the excitement and secrecy surrounding Bletchley. He relished the way that
>> ... old procedures, like the setting up of agents, the suborning of informants, the sending of messages written in invisible ink, ... all turned out to be largely cover for this other source, as one might keep some old-established business in rare books going in order to be able, under cover of it, to do a thriving trade in pornography and erotica.
2nd level quote from Muggeridge, "Chronicles of Wasted Time" (1973) p139
> Churchill's romantic soul loved the excitement and secrecy surrounding Bletchley. He relished the way that
>> ... old procedures, like the setting up of agents, the suborning of informants, the sending of messages written in invisible ink, ... all turned out to be largely cover for this other source, as one might keep some old-established business in rare books going in order to be able, under cover of it, to do a thriving trade in pornography and erotica.
2nd level quote from Muggeridge, "Chronicles of Wasted Time" (1973) p139