Preheat the oven to 160C/325F/gas mark 3
Use a 23cm/9 inch round cake tin.
Grease and line the cake tin. Add boiling water to the orange juice, rind and melted margarine to make 3/4 cup. Sift together twice - flour, salt, baking powder and sugar. Add the juice and rind of the orange. Add the nuts and cranberries, mix all the ingredients, pour into the cake tin and bake for one hour, or until a warm knife inserted into the centre comes out clean. Leave to cool for 10 minutes, before placing on a wire rack to cool completely.