On a Sunday we always have a bacon butty midday and a big roast meal early evening.
The bacon butty is still dinner, and the roast is still tea. Even though we might say "are we having a Sunday Dinner for tea today?"
(We'd probably have it at dinner time, but our lass works half day most Sundays.)
As for "meal in-between" - in between what?
I don't have breakfast, I only eat two meals a day, so neither (or both if you ignore sleep) is in-between meals.
Tea is
both a drink (a bloody awful one at that) and a mealtime. A mealtime in the early evening. When Americans might call it dinner. But that's foreigners for you - they do things differently and they call things different names.
I'm English, and a Yorkshire man, and I call stuff what it properly is.
Don't bother quoting your fancy sources. I'm right and won't be swayed by your false arguments.