6.—(1) If the works are not substantially commenced within ten years from the coming into operation of this Order or such extended time as the Minister may in the circumstances by Order direct the powers conferred on the Commissioners by article 4 (Power to construct works) of this Order shall cease.
(2) If the execution of any of the works after having been substantially commenced is virtually suspended for twelve consecutive months the said powers in respect of that work shall cease except as to so much thereof as is then completed unless the Minister by Order directs that the said powers continue and remain in force.
(3) A certificate of the Minister to the effect that the works have not been substantially commenced or that they have been virtually suspended for twelve consecutive months shall for the purposes of this article be conclusive evidence of the facts stated in such certificate.