6The purposes referred to in paragraph 4 of this Schedule are—
(a)the purpose of avoiding or reducing danger to navigation, to persons engaged in and vessels and equipment used for fishing, to some structure or apparatus (which may be the pipe-line) or to marine flora or fauna ;
(b)the purpose of facilitating the use of the pipe-line by persons other than the applicant where it appears to the Secretary of State that such persons desire to use the pipe-line;
(c)the purpose of avoiding or reducing interference with fishing or the exploitation of mineral resources;
(d)any other purpose which the Secretary of State considers proper;
and it shall be the duty of the Secretary of State to state the reasons for his opinion in any notice of his opinion served in pursuance of paragraph 4 of this Schedule except any reason which he considers that it would be against the national interest to state.