Preheat oven to 350 degrees F. Grease a 9×5-inch loaf pan and set aside.
Measure out ¼ cup of the sharp cheddar, ¼ cup of the white cheddar and 2 tablespoons of the Dubliner and reserve for topping the bread later.
In a large bowl, combine the remaining cheese, the flour, baking powder, dry mustard, salt, cayenne, white pepper, and garlic. Stir to ensure that all of the cheese is coated with flour.
In a small bowl, whisk together the beer, sour cream, egg, and Worcestershire sauce.
Pour the beer mixture into the cheese and flour mixture. Use a wooden spoon or spatula to mix the dough until just combined. Spoon the dough into the prepared loaf pan, using a spatula to even out the top. Mix together the reserved cheeses and sprinkle evenly on top.
Bake for 55 to 65 minutes or until a knife inserted into the center comes out clean (or, if you have an instant-read thermometer, the middle of the bread reaches 190 degrees F).
Remove bread from the oven, place on a wire rack, and cool for 10 minutes. Run a knife along the edges of the pan and continue to cool. When the bottom of the pan can be touched, turn the bread out and let cool completely on a wire rack before slicing.