Preheat oven to 350°. Grease 9 x 5-inch loaf pan with margarine.
Place dates, baking soda and salt in medium bowl; pour hot water over top. Allow to cool.
Sift flour and baking powder together twice into medium bowl. Cut margarine into flour. Drain dates; mix into flour. Mix walnuts and sugar into flour. Beat in egg. Pour batter into greased pan.
Bake in preheated oven until wooden pick inserted into center comes out clean, about 1 hour. Let cool in pan 10 minutes. Remove from pan. Place on wire rack to cool.
Variation: Substitute currants for raisins or dates.