My PC issues continue so updates are a little sporadic at the moment, sorry about that.
I’d noticed this letter box built into the side of, what is now, a private house in Stutton, the next village along from where I work.
I’ve not come across the George V letterboxes before. We have a slightly older Victorian box in Dunmow, but this one seemed somehow older even though George V reigned between 1910 and 1936