In London, local could mean any global flavor, but for pure Britishness, roast beef and Yorkshire pudding probably top the list. If you want the best-value traditional Sunday lunch, go to a pub. Gastropubs, where Sunday roasts are generally made with top-quality ingredients, are a good bet. The meat is usually served with crisp roast potatoes and carrots, and with the traditional Yorkshire pudding, a savory batter baked in the oven until crisp. A rich, dark meaty gravy is poured on top.
Other tummy liners include shepherd's pie, made with stewed minced lamb and a mashed-potato topping and baked until lightly browned on top; cottage pie is a similar dish, but made with minced beef instead of lamb. Steak-and-kidney pie is a delight when done properly: with chunks of lean beef and ox kidneys, braised with onions and mushrooms in a thick gravy, and topped with a light puff-pastry crust.
Fish-and-chips, usually cod or haddock, comes with thick "chips," or french fries, as we call them in the States. A ploughman's lunch in a pub is crusty bread, a strong-flavored English cheese with bite (cheddar, blue Stilton, crumbly white Cheshire, or smooth red Leicester), and tangy pickles with a side-salad garnish. For a hot, comforting dessert, seek out a sweet bread-and-butter pudding, made from layers of bread and dried currants baked in creamy custard until crisp. And one can't forgo English cream tea, which consists of scones served with jam and clotted cream, and sandwiches made with wafer-thin slices of cucumber -- served as an accompaniment to properly brewed tea.