Where, after the commencement of this Act, any premises are sub-let either in whole or in part by the tenant with the previous consent in writing of the landlord, the tenant or the sub-tenant to whom the premises are sub-let may, in the prescribed manner, give notice to the landlord of the creation of the sub-tenancy within one month of the date of such sub-letting and notify the termination of such sub-tenancy within one month of such termination.