The reference in section 6 of the Telegraph Act 1878 (which empowers the Postmaster General to establish telegraphic lines on certain undertakings) to an Act of Parliament passed after 1st January 1878 shall be construed as including references to a harbour revision order and to a harbour empowerment order, and the reference in section 7 of that Act (which makes provision as to work done in the execution of certain undertakings which involves alteration in telegraphic lines) to an Act of Parliament shall be similarly construed.