Sift the flour with baking powder and salt. Set aside.
Beat egg and add sugar slowly. Blend in 1 tablespoon butter or margarine. Stir in dates and nuts. Gradually add flour mixture, mixing well.
Pour into a greased 25cm square pan, spreading evenly. Bake at 165 degrees C for 25-30 minutes. Cool in pan on wire rack. Spread top with glaze and cut into 24 sticks.
To Make Glaze: Combine 1 tablespoon milk, 1 tablespoon margarine, 1 cup icing sugar, 1 teaspoon lemon juice and 1/2 teaspoon grated lemon rind. Heat over low heat until well blended. Cool slightly before pouring over biscuits.