The mediator so named shall expeditiously meet with the disputing parties or their representatives and shall exert every reasonable effort to effect a prompt settlement of the labor dispute. After the appointment of a mediator by the Governor, as provided for in section 5 hereof,¹ there shall be no interruption of work and no strikes or slowdowns by employes, and there shall be no lockout or other work stoppage by the employer, until such time as all of the procedure provided for in this act has been exhausted, or during the effective period of any order issued by a board of arbitration pursuant to the provisions of this act, unless the Governor shall determine that failure to settle the dispute would not cause severe hardship to be inflicted on a substantial number of persons.