71Nothing in the provisions of this Act specified in Part I of Schedule 19 to this Act shall authorise the execution of any works (whether of construction, demolition or alteration) on, over or under tidal lands below high-water of ordinary spring tides, except—
(a)with the consent of any persons whose consent would have been required if this Act had not been passed ; and
(b)in accordance with such plans and sections, and subject to such restrictions and conditions as may be approved by the Board of Trade or the Secretary of State before the works are begun.