(2) Of the four copies so furnished one shall be signed in the case of a company by the chairman and two directors and by the principal officer of the company and, if the company has a managing director or managing agent, by that director or managing agent, in the case of a firm, by two partners of the firm, and, in the case of an insurer being an individual, by the insurer himself 1[ and one shall be signed by the auditor who made the audit or the actuary who made the valuation, as the case may be].