No person shall engage in the business of operating a motor vehicle as a common carrier of passengers between points in this state unless he holds a certificate issued by the department authorizing such operations; provided, however, that, if he or his predecessor in interest, including street railways operating motor vehicles in substitution for or in connection with street car operations, was engaged in bona fide operation as a common carrier over regular or irregular routes, by motor vehicle, as provided by the definitions in N.H. Rev. Stat. § 376:2, V and VI, on June 13, 1941, over the route or routes or within the territory for which application is made and has so operated since that time, or, if engaged in furnishing seasonal service only, was in bona fide operation on said date during the season ordinarily covered by its operation, except in either instance as to interruptions of service over which the applicant or his predecessor in interest had no control, the department shall issue such certificate without requiring further proof that the public convenience and necessity will be served by such operation, and without further proceedings, if application for such certificate is made to the department as provided by N.H. Rev. Stat. § 376:9, on or before April 1, 1942. Otherwise, the application for such certificate shall be decided in accordance with the procedure provided for in N.H. Rev. Stat. § 376:5 or 376:8 and such certificate shall be issued or denied accordingly. Pending action on any application, the continuance of such operation shall be lawful.