(1) Where a prospectus invites persons to subscribe for shares in or debentures of a company, every person who is a director of the company at the time of the issue of the prospectus, and every person who has authorised the naming of him and is named in the prospectus as a director or as having agreed to become a director either immediately or after an interval of time, and every promoter of the company, and every person who has authorised the issue of the prospectus, shall be liable to pay compensation to all persons who subscribe for any shares or debentures on the faith of the prospectus for the loss or damage they may have sustained by reason of any untrue statement therein, or in any report or memorandum appearing on the face thereof, or by reference incorporated therein or issued therewith, unless it is proved -
(a) With respect to every untrue statement not purporting to be made on the authority of an expert, or of a public official document or statement, that he had reason