Rub the fat into the flour until the mixture resembles fine crumbs. Sift in the sugar, almonds, spice and soda. Scatter the currants and raisins over the mixture. Mix to a soft dough with the milk. Place the mixture in an 8-9 inch round cake tin, greased and lined with foil or parchment paper. Leave overnight. Next day, bake at 325°F, 170°C, gas mark 3 for one hour, then reduce the heat to 300°F, 150°C, gas mark 2 for a further one and a half hours or until the cake is springy and brown. Cool well on a wire rack before cutting.