Preheat the grill to high. Set the oven to its lowest heat and pop 2 plates in it to keep warm. Put the sausages, mushrooms and tomatoes, scored-side up, on to a large grill pan and place under the grill, about 5cm from the heat. Cook for about 10 minutes, turning the sausages once or twice.
Add the bacon and black pudding to the pan and grill for 5 minutes, turning halfway through cooking, until they are cooked and crispy. Put the baked beans in a saucepan and warm gently for 2 to 3 minutes, stirring occasionally.
Place a non-stick saucepan over a low heat. Melt 1 knob of butter in the pan, add the eggs, season to taste and stir gently until just scrambled. Remove from the heat. Put the bread in the toaster, and arrange the sausages, mushrooms and tomatoes with the bacon, black pudding and beans on the warm plates. When the toast pops up, butter it, then put a slice on each plate and top with scrambled egg. Serve with HP sauce or tomato ketchup on the side, and a pot of tea.