6U.K.The undertakers shall, after the manner of construction and the line and situation of any necessary alternative apparatus have been agreed or determined as aforesaid, and after the grant to the undertakers of any such facilities and rights as are referred to in paragraph 4 above, proceed with all reasonable dispatch to construct and bring into operation the alternative apparatus and thereafter to remove any apparatus required by the appropriate authority to be removed under the provisions of this Part of this Schedule and, in default, the appropriate authority may remove the apparatus.