Cream butter and sugar. Beat in egg until light and fluffy. Stir in rum and vanilla. Sift all dry ingredients together. Add to butter-sugar mixture, alternately with bananas, mixing well after each addition. Fold in remaining ingredients. Pour into well buttered and floured loaf pan. Bake in 350 oven for 1 hour and 15 minutes, until bread shrinks from sides of pan. Cool 30 minutes then unmold. Wrap tightly in foil. Serve at room temp. With plenty of sweet butter.