• If you call it “tea”, and eat it at around half past six, you are almost certainly working class or of working class origin. (If you have a tendency to personalize the meal, calling it “my tea”, “our/us tea” and “your tea” - as in “I must be going home for my tea”, “what’s for us tea, love?” or “Come back to mine for your tea” - you are probably northern working class.)
• If you call the evening meal “dinner”, and eat it at around seven o’clock, you are probably lower-middle or middle-middle class.
• If you normally only use the term “dinner” for rather more formal evening meals, and call your informal, family evening meal “supper” (pronounced “suppah”), you are probably upper-middle or upper class. The timing of these meals tends to be more flexible, but a family “supper” is generally eaten at around half past seven, while a “dinner” would usually be later, from half past eight onwards.

*sometimes I dislike idiomatic usage* D：