There was a bit on radio 2 about a month ago that I think can shed light on the tea vs dinner debate.
The aristocracy would take afternoon tea (you know the sort- earl grey, cucumber sandwiches with no crust, jam and scones etc) around 3pm.
The folk serving them, once they had finished clearing up, would then have something to eat, known as ‘high tea’. The difference from afternoon tea simply being the temperature of the food. Normally eaten between 430 and 6pm
Then at around 8, dinner would be served to the aristocracy.
Iirc supper was what was left over for the servants.
So, if you are anything other than the aristocracy, it’s tea.