The Minister may by order assign some other description to the highways which for the time being are principal roads for the purposes of any enactment or instrument (whether by virtue of section 12(1) and (2) above, or by virtue of having been so classified under section 12(3) above, or otherwise).
If an order is made under subsection (1) above, then, except in so far as the order otherwise provides, any reference to a principal road in any enactment or instrument passed or made before the order is made (including an enactment in this Act) is to be construed as a reference to a highway of the description specified in the order.
Nothing in subsection (1) above affects the power of the Minister under section 12(3) above to classify highways or proposed highways in such manner as he may determine after consultation with the highway authority concerned.