Heat a grill until hot. Place the halved baps cut side up under the grill until toasted and golden brown. Remove and set aside.
Heat a thin layer of oil in a large non -stick frying pan and add the sausages and hash browns, if using. Fry for 10-15 minutes, or according to pack instructions. Remove the sausages and hash browns and set aside on a large plate lined with kitchen roll. Add the bacon and cook for 3-4 minutes each side, or until crispy. Remove the bacon and place on the plate with the sausages and hash browns.
Add the tomato, cut side down and the mushrooms to the frying pan. Crack the egg on a work surface and add to the frying pan. Fry the tomato, mushrooms and egg for 3-4 minutes on a medium heat. Turn the tomato and mushrooms half way through the cooking time. Spoon the oil over the egg every now and then. The egg white should be set and the yolk still runny when cooked. Remove the tomato, mushrooms and egg from the frying pan and place on the plate with the sausages, hash browns and bacon.
Lightly butter the toasted sides of the bap, if using. Now the fun part, build your English breakfast bap. Its probably easier finishing with the fried egg and a sprinkling of pepper and a dollop of your favourite sauce! Put the bap lid on. Eat straight away with a mug of tea or coffee.