The application and the statement accompanying it shall be signed-

(a) in the case of an employer by the employer himself, or when the employer is an incorporated company or other body corporate, by the agent, manager or other principal officer of the Corporation;

(b) in the case of workmen, either by the President and Secretary of a trade union of the workmen, or by five representatives of the workmen duly authorized in this behalf at a meeting of the workmen held for the purpose;

3[(c) in the case of an individual workman, by the workman himself or by any officer of the trade union of which he is a member or by another workman in the same establishment duly authorized by him in this behalf :

PROVIDED that such workman is not a member of a different trade union.