Wow, a 2 year discussion on meal titles, how marvellous!
To add my tuppence worth, I am English (London), middle class, and have been brought up on breakfast, lunch and dinner. Dinner is generally at around 7pm, so I fit into an earlier description of middle classdom there.
Tea is a drink, or a break from work at around 11am and/or 3pm. A tea break is also often a polite version of cigarette break!
An exception is Christmas dinner, which is usually late afternoon/early evening.
As has been touched upon previously, at my school we either went to see the dinner ladies or brought in a packed lunch. I can only assume from that that there must be some relationship between the name of the meal and its temperature...
I have also taken on what I assume is an Americanism, namely 'brunch', which loosely translated usually means I a)have overslept or b) have a hangover, and so breakfast is delayed until late morning.
In addition to all this, I have also been known to have 'elevenses' (a light snack mid morning), and afternoon tea (usually when visiting a seaside cafe on the south coast of England, consisting of tea and scones. I believe this is also available at the Ritz if you are passing by). Although I guess these are just more elaborate forms of the tea break mentioned above.
I brief poll of my colleagues (all 2 of them) has produced roughly the same answers as mine... but I suppose the fact that we all middle class and from the south of England means that that was almost inevitable, wasn't it?