Before you start this recipe, preheat the oven to 230`c. Mix together all the dry ingredients and rub in the butter. Make a well in the centre, and add in the beaten egg and ¾ of the buttermilk. Mix the ingredients together using your hand till you have a soft, but not sticky dough (you may need to add the remaining buttermilk) Turn the dough out on a floured surface and knead lightly to a round. Flatten slightly to a thickness of 2 inches and place on a floured baking sheet. Sprinkle some flour over the top and cut a deep cross in the soda bread round. Place the baking sheet into the preheated oven and bake for 20 minutes, then turn down the heat to 200`c and continue to cook the bread for 20-25 minutes more. When cooked, the soda bread should sound hollow when tapped. Remove he bread from the oven and allow to cool slightly before serving whilst still warm.