h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Where I come from Lunch is called Dinner, and Dinner is known as Tea. At school, 'Lunch Time' was a break we had at 10:30, at 12:00 we had Dinner and then at night we had Tea.

Does anyone else use Breakfast, Dinner and Tea as the labels for their mealtimes?

Yes, it may be considered correct to use lunch for midday meal & dinner for the evening meal but we tend to say breakfast, dinner & tea (or supper if it's late!)regardless of how substantial the meal is. The exception is if we are having a special evening meal & then it's a light lunch at midday!
Probably it's because the children had their main meal midday.
Actually this just made me curious enough to check in my Chambers dictionary where dinner = 'the chief meal of the day', lunch = 'a slight repast between breakfast & midday meal: midday meal: snack at any time of day'.
So take your pick!

In my experience Dinner is in use as a common (or the primary) word for the midday meal in Wales and Northern England. I have never met anyone in South-East England (where I currently live) who even recognises the use of Dinner this way.
Maybe it was originally a class thing based on when you had your largest meal? A physically demanding job might require more 'fuel' earlier in the day?

I use lunch to humour my work colleagues but I only eat dinner - hence I can truly say I have NEVER eaten lunch in my life.

Well, all I can say is "Hooray!" I would much rather have dinner than lunch anytime!