Preheat the oven to 350 . Cream the butter with the sugar until light and fluffy. Beat in the eggs. Sift together: flour, baking powder, baking soda, and salt, and add alternately with the chopped nuts to the creamed butter mixture. When these ingredients are well combined,stir in the nuts and the lemon peel. Spread the batter into a lightly greased 9x5x3" loaf pan and bake in the center of the oven for 45 to 55 minutes. Cool on a wire rack.