RP was in the process of being formalized at that point. It was a BBC project (I exaggerate slightly)[1]. The Queen’s accent used to be distinctly non Received

RP was in the process of being formalized at that point. It was a BBC project (I exaggerate slightly)[1]. The Queen’s accent used to be distinctly non Received Pronunciation if you listen to early twentieth century recordings. Stone Masons would almost universally have been literate because you need to engrave things. Half assed graffiti could be someone who was less a skilled tradesman than a member of the guild but guild members would have been expected to be able to read the Bible at least. Knowing how to spell your own name is not a big thing if you can read the KJV. And t->k is not a sound shift observed in historical language changes. [1] RP probably received its greatest impetus, however, when it was selected in 1922 by the BBC Advisory Committee on Spoken English as a broadcasting standard – hence the origins of the term BBC English. The Committee believed Standard English, spoken with an RP accent, would be the most widely understood variety of English, both here in the UK and overseas. Members of the committee were also conscious that choosing a regional accent might run the risk of alienating some listeners. https://www.bl.uk/british-accents-and-dialects/articles/received-pronunciation https://www.bl.uk/british-accents-and-dialects/articles/rece...