Here we go. I found this in the "Going Back" column of Practical Wireless, August 1970. The quote here is from 1932:
How Germany does it -- In Germany the listening tax is paid monthly and its collection from set owners is made by the postman on his rounds. The annual cost is approximately 30s. Radio pirates are discovered by the municipal chimney-sweeps who in the course of their daily duties visit all houses, flats and apartments. It is their duty to notify all wireless receivers to the local authorities.
Chimney sweeps as government snoops. What
would Dick Van Dyke say?