Preheat the oven to 350˚F
In a large bowl, beat the butter, sugar and orange zest until fluffy, then beat in the egg.
In a small bowl, stir together the flour, baking powder, baking soda and salt.
Add to the butter mixture in three additions, alternating with the juice in two.
Add the cranberries along with the final addition of flour.
Pour into a greased or parchment-lined 8x4-inch loaf pan and bake for 1 hour, or until springy to the touch.