Britain's first fish and chip shop opened in London in 1860. It is not clear exactly how and when the battered fish first met the deep fried potato but historians interested in that sort of thing often cite Jews in the east end of London selling (cold) fried fish in the street as a precursor. There was also a tradition of potatoes as street food but these were baked and not fried.
In spite of concerns over dwindling fish stocks and the consequent escalating price of fish, there are still over 10,000 shops in Britain selling affordable, takeaway meals to people from all walks of life. My lunch cost just under a fiver and included the fluorescent green mushy peas, the scarlet ketchup, copious amounts of salt (which helps the fish batter stay crisp though the chips remain resolutely soft) and lashings of malt vinegar.
Deep frying fish makes eminent sense as the batter protects the flesh from overcooking and drying out. My rock eel was really juicy as was Abi's piece of haddock. Some people leave the batter but we couldn't resist the salty, fatty crunch contrasting with the moist fish flesh within and the unmistakeable taste of beef fat.
To drink, something sharp and fizzy is good to cut through all that stodge: I think a traditional India Pale Ale is good (there is an excellent one made at the nearby Grain Brewery) or sparkling wine, if not actually Champagne. Crisp, zesty Sauvignon Blanc would work too (from the Loire Valley or South Africa). And if eating fish and chips in the south of Spain (at the Codfather in Nerja perhaps) a dry Sherry or Montilla would be perfect.