But obviously saying it with anything other than long i in the modern day is weird and borderline insane and/or American (or, apparently, New Zealandish for an early primary school class)
Seems there is clearer evidence of origin than I thought (particularly given competing origin myths were already there within a couple of decades). Anyway, this is the book: www.bloomsbury.com/uk/ok-978150...
Not only from backroom abbreviations - these were a bit of a fad in expanding newspapers, helping to build an 'in-group' readership language, like so many publications since. Most died away, but OK had become widespread in a particular political context and survived.
Michelle McSweeney's recent book on the subject (which I have just discovered I can access through the library, hurrah!) paints a convincing explanation of the process by which OK arose. Also contemporary: k. g. for “no go” or “no good” (kno go/ kno good), and k. y. for “no use” (kno yuse).
As that petition to parliament nears 3 million signatures - and is still waiting on a date for the parliamentary debate - I wrote some of my thoughts about UK Labour's adventures in digital ID.
In the days of local exchanges, my grandparents' number was 9996. (This raised some eyebrows, but I don't know if there was a period when it actually caused a problem.)