This was done by “mail order bride” companies like those in Russia and Ukraine, that charge per message or letter sent back and forth, using their platform that does not allow for contact information to be shared; you are not talking to Anastasia but “Hairy Boris”!
Later scams evolved to use prerecorded video clips etc. Which I assume is next for OF also.
Laurie Lee was born in 1914 and as a child, witnessed these changes, but he could also know from interacting with those much older, how little the basic rhythms of life had changed up until then.
Literacy in earlier years, from a quick search, still seems to be debated as the line for literacy is whether the person could sign their name to the marriage register, which is a low bar.