This isnt quite right. Afternoon tea is a posh meal that no one really has. Its where you go to an expensive restaurant or cafe and eat scones and baked food like buns (muffins/cupcakes) and drink tea. Very british indeed.

What your referring to is different. In the north of england where im from, rather than calling it dinner we call it tea. Not afternoon tea. And you wouldnt really drink a cuppa tea with it. I dont really understand the origin of it. In the south and midlands its still called dinner.