That's because in Victorian times the lower classes often couldn't afford a meal at that time and had to subside on some tea and perhaps a slice of bread.
The use of "tea" for that meal remains a class signifier; my paternal grandmother used it, my parents did not (my mother, despite not being a native speaker, presumably is the one who eradicated it from my father's vocabulary), and yet I continue to say unwittingly say it occasionally though I now live in the USA. A vestigial Australianism in my case
It's definitely "non-U" in the UK, though that whole world is mostly gone.
The use of "tea" for that meal remains a class signifier; my paternal grandmother used it, my parents did not (my mother, despite not being a native speaker, presumably is the one who eradicated it from my father's vocabulary), and yet I continue to say unwittingly say it occasionally though I now live in the USA. A vestigial Australianism in my case
It's definitely "non-U" in the UK, though that whole world is mostly gone.