I grew up with breakfast, dinner, tea and supper, the latter being a couple of biscuits or bowl of cereal before bed.
Not once in my childhood did I hear the cry of "come in for your lunch" when it was time for friends to stop playing and head home to eat.
Nowadays, it is all very mixed up.
I've lived 'darn sarf' (well, sort of - just south of the Watford Gap, anyway) for over 30 years now, where most people nowadays seem to have lunch and dinner.
Gradually, I've gone over to saying 'lunch', but it still really grates on me to say 'dinner' instead of tea, so only do it occasionally, if I think the listener might get confused otherwise. My posher grandchildren soon got used to the fact that what they call dinner is called tea at Grandma's. We have a laugh about it sometimes ☺
I don't mind what words people use for these meals, as long as they don't sneer at other people's versions, as if their own preferences are somehow the only 'correct' ones!