Even then

'Mustn't crab the Government, though! Don't know really what we'd do without it. I can tell you that nowadays you can walk in most anywhere with a notebook and pencil, dressed right, and speaking B.B.C., and ask people all the most intimate details of their daily lives and all their back history, and what they had for dinner on November 23rd because that was a test day for middle-class-incomes - or whatever it happens to be (making it a grade above to butter them up!) - ask'em any mortal thing you can; and nine times out of ten they'll come across pat, and even the tenth time though they may cut up rough, they won't doubt for a minute that you're what you say you are - and that the Government really wants to know - for some completely unfathomable reason!… it's the best line we've ever had… Yes, Government snooping is God's gift to investigators and long may it continue!'

(Agatha Christie, After the Funeral, first published 1953)