Paragraph 15 above does not apply to advice given in a newspaper, journal, magazine or other periodical publication if the principal purpose of the publication, taken as a whole and including any advertisements contained in it, is not to lead persons to invest in any particular investment.

The Secretary of State may, on the application of the proprietor of any periodical publication, certify that it is of the nature described in sub-paragraph (1) above and revoke any such certificate if he considers that it is no longer justified.

A certificate given under sub-paragraph (2) above and not revoked shall be conclusive evidence of the matters certified.