Without a doubt, every visitor to London, or England in general, should try a full English breakfast. Traditionally, this includes bacon, poached or fried eggs, fried mushrooms, toast, sausages, fried or grilled tomatoes, and baked beans. Yes, baked beans for breakfast. As almost everything is fried, it is oftentimes referred to as a "fry-up." If you have a full day of tourist attractions and exploring ahead of you, there is no better way to fill up your stomach. Plus, the breakfast will include hot tea or coffee.
Most restaurants serving breakfast and lunch will have this item on their menu. However, Workers Café is quick, and reasonably priced. For less than £5 (about $7), you can come in hungry, and leave stuffed and ready for a day in the city.