Preheat oven to 350 degrees F (175 degrees C). Grease and flour a loaf pan.
In a large bowl, combine flour, salt, baking powder, baking soda, and sugar.
In a 1-cup (or larger) measuring cup combine juice and zest of the orange, butter and enough boiling water to reach 3/4 cup. Stir into flour mixture. Fold in egg, walnuts and cranberries. Pour batter into prepared pan.
Bake in preheated oven for 1 hour, or until a toothpick inserted into the center of the loaf comes out clean. Cool loaf in the pan for 5 minutes before removing to a wire rack to cool completely.
To make the icing combine confectioners' sugar, butter, orange juice and milk; add more milk if necessary so that the icing is thin and slightly runny. Drizzle over bread; allow icing to set before slicing.
