The use of dinner or tea is often employed as a prime example of England’s North-South division. The Oxford English Dictionary lists tea as “a light meal in the late afternoon, but locally in the U.K. (esp. northern), […] a cooked evening meal” (OED 2013), which suggests that tea is indeed a Northern form.
This variable shows clear regional stratification. Tea is evidently favourable in the North, with dinner predominant in the South. London in particular shows huge contrasts: 89% favour dinner compared to the mere 3% that favour tea.