Put the dates in a slightly big bowl (you'll be mixing the batter in this) and sprinkle the baking soda over the dates. Pour the hot water over this so it covers the dates.
Keep aside for about half an hour till the dates soften up and the water cools down.
Stir in the sugar, eggs, butter, milk and vanilla into the date mixture. Sift the all purpose flour, salt and the baking powder together. Add to the bowl along with the walnuts. Gently mix in this in till everything just combines. Do npt over mix.
Spoon the batter into a parchment lined (bottom of tin only), greased and floured 7" round cake tin. You may use a loaf tin if you choose.
Bake at 180C (350F) for about 60 minutes till cooked or till a skewer inserted into the cake comes out clean. If the cake starts browning too quickly, cover it with aluminium foil.
Let the cake sit in the tin for 5 minutes, then unmould. Cool on a rack and serve with coffee or tea.