Sift & mix the flour, baking soda, baking powder, cinnamon & salt. Add the oil & sugar. Mix well. Stir in the carrots & walnuts. Enusre that all is well mixed. Transfer to a floured & greased cake tin approx. 20 cm X 20 cm. Bake at 350F for about an hour or until a knife inserted in the centre of the cake comes out clean. Cool for a few minutes on a wire rack. Turn out & let cool completely.