(5) If for any reason the Chairman of the Board or the Chairman of the Executive Committee is unable to attend any meeting of the Board or, as the case may be, of the Executive Committee,--
(a) in the case of the meeting of the Board, a director 5[ authorised by the Chairman of the Board in writing shall preside at such meeting, but if the director so authorised is absent or if no such authorisation has been made, the Board may elect a director to preside at that meeting; and
(b) in the case of the meeting of the Executive Committee, a member authorised in writing by the Chairman of that Committee shall preside at that meeting, but if the member so authorised is absent or if no such authorisation has been made, the Committee may elect any of its members to preside at that meeting.]