Grease a medium 12 cm x 22 cm loaf pan. Line base and sides with baking paper.
Place dates in a large heatproof bowl. Sprinkle with soda. Pour over 1 cup boiling water. Stand 40 minutes, or until cool. Stir in sugar, eggs and oil until combined.
Sift flour over mixture, returning any husks remaining in sieve to bowl. Add spice and ½ cup of the walnuts. Stir until combined. Spoon mixture into prepared pan. Sprinkle with remaining walnuts.
Bake in a 160 °C oven (fan-forced) for 45-50 minutes, or until a skewer inserted in centre comes out clean. Stand in pan 10 minutes. Turn onto a wire rack to cool. Serve sliced.