WW1 and WW2 did a number on trad Brit food. Especially after the rationing of WW2, a lot of Brits simply didn't have access to anything other than processed garbage, supplemented with the most basic vegetables (peas, cabbage, carrots and potatoes).
Hugh Fearnley-Whittingstall and River Cottage opened my eyes to pre-rationing style trad British food.
People have horror pictures of jellied eels and pie, mash and liquor, but nobody remembers the amazing cakes and baked goods, proper Cornish pasties, roast venison, rabbit casserole, game hens, not to mention Britain's highly underrated seafood. Hell, roast beef and the very concept of 'steak' are British.
If all you choose to eat is monster munch and angel delight don't go about claiming Brit food is shit, because you come across as never having had any.