Preheat the oven to 415 degrees F (200c/gas mark 6).
The day (or up to 2 days) before you load them, prick all 10 potatoes, then bake the potatoes until the skins are crisp and the insides floury, about 1 to 1 1/2 hours. As soon as you can bear to tackle the hot potatoes, cut them in half lengthwise and scoop the insides into a bowl. Put the husk-like skins of the potatoes on a tray and, when cool, cover until you are ready to fill them. Let the potato cool in the bowl, and then cover until needed.
When you are ready to fill the potatoes, preheat the oven to 415 degrees F (200c/ gas mark 6). Add 7 ounces (200g) of grated Cheddar to the cold potato along with the sour cream. Finely chop the spring onion and add to the potato, with the salt, pepper and Worcestershire sauce. Spoon the potato filling into the potato skins, and lay each half on a baking tray so they fit snugly together. Sprinkle with the remaining cheese, giving each potato skin a light covering, and cook until golden, about 20 to 30 minutes. In a large saute pan, over medium heat, add enough oil to coat the bottom of the pan. Fry the bacon rashers in the oil, or grill them, until crispy. Remove them to a paper towel lined plate and then crumble. Sprinkle each potato skin with the bacon to make them fully loaded. Transfer the potato skins to a serving platter and serve.