Sift together flour, baking powder, soda and salt
Cream butter, gradually beat in sugar.
Add eggs, one at a time, beating well after each.
Add banana and mix well.
Blend in sifted dry ingredients: fold in nuts.
Pour into greased (buttered), 9x5x3 inch loaf pan
Bake in a moderate (350 degree) oven for 60 to 70 minutes.
Cool thoroughly before slicing.