All notices, consents, approvals, demands and other documents authorised or required by or under this Act or any local enactment incorporating any provisions of Schedule 4 to be given, made or issued by the Secretary of State or any F1local authority, or water authority F2, and all notices and applications authorised or required by or under this Act or any such local enactment to be given or made to the Secretary of State or to, or to any officer of, any F1local authority, or water authority F2, shall F3, subject to section 23(4) of and paragraph 4(1) of Schedule 3 to this Act, be in writing.