21. (1) Subject to subsection 5 of this section, benefit shall not be payable unless notice of the accident is given as soon as practicable after the happening thereof and before the workman has voluntarily left the employment in which he was injured and unless the claim for benefit is made within six months from the happening of the accident, or, in case of death, within six months from the time of death.
(2) The notice of the accident shall give the name in full and address of the worker and shall be sufficient if it states in ordinary language the cause of the injury and where the accident happened.
(3) Such notice may be served by delivering it at the place of business or the residence of the employer, or may be notified by sending it by registered mail to either place, or, where the employer is a partnership or legal person, by delivering it at the office of the employer, or, if there are more offices than one, at any of the offices of such employer, or sending it by registered mail to any of such offices.
(4) Where the benefit is payable out of the accident fund, such notice shall also be given to the Commission by delivering it at the office of the secretary or by sending it to him by registered mail addressed to his office.
(5) Failure to give the prescribed notice or to make such claim, or the existence of any irregularity or inexactitude whatever in such notice or claim, shall not bar the right to benefit if, in the opinion of the Commission, the employer was not prejudiced thereby or, where the benefit is payable out of the accident fund, if the Commission is of the opinion that the claim for benefit is a just one and ought to be allowed.