Preheat the oven to 180C/350F/gas mark 4
Use a 900g/2 lb loaf tin.
Sift together the flour, baking powder and salt. Cream the butter and sugar until light and fluffy. Add the sour cream and orange peel, beating well. Mash the bananas, combine with the milk and add to the creamed mixture alternately with the flour mixture. Beat until smooth after each addition. Stir in the nuts. Turn into the greased loaf tin. Bake for 45 to 50 minutes. Leave to cool in the tin for 10 minutes, and turn out onto a wire rack.
