With respect to any harbour, port, bay, estuary, or navigable river, or part thereof, comprised in any notice from time to time given by the Admiralty under section nine of “The M1Harbours Transfer Act, 1862,” previously to commencing any work below high-water mark there shall be deposited at the Admiralty Office plans, specifications and working drawings thereof for the approval of the Admiralty, such approval to be signified in writing under the hand of the Secretary of the Admiralty, and with respect to all other parts where the tide flows, previously to commencing any work below high-water mark there shall be deposited at the office of the Board of Trade plans, specifications, and working drawings thereof for the approval of the Board of Trade, such approval to be signified in writing under the hand of one of the secretaries of the said Board, and any such work shall be constructed only in accordance with such respective approval; and when any such work shall have been commenced or constructed, it shall not be lawful at any time to alter or extend the same without obtaining, previously to making any such alteration or extension, the like respective consent and approval; and if any such work shall be commenced or completed, or be altered, extended, or constructed, contrary to the provisions of this Act, it shall be lawful for the Admiralty or the Board of Trade, as the case may require, to abate, alter, and remove the same, and to restore the site thereof to its former condition, at the cost and charge of the person or company that executed the said work, F1. . ..