Preheat the oven to 160C/325F/gas mark 3
Use a 20cm/8 inch cake tin.
Grease and line the cake tin. Steep the currants in the apple juice until plumped. Rub the butter into the flour until the mixture resembles fine bread crumbs. Sift together the nutmeg, baking powder, bicarb. and sugar and add to the mixture. Mix the sour cream into the buttermilk with the lemon juice. Make a well in the dry ingredients. Mix in the apple juice, with the steeped currants and the buttermilk alternately, adding about one-third each time. Mix thoroughly to blend. Place the mixture in the cake tin and bake for two hours or until the cake is springy and brown. Cool well before cutting.
