626 It may be mentioned that clause (rr) of section 43(2) of the new Act provides as follows: "where any permission referred to in Section 3 of the old Act has been obtained on any ground specified in sub section (1) or sub section (2) of section 21 and has become final, either before the commencement of this Act or in accordance with the provisions of this sub section after the commencement of this Act (whether or not a suit for the eviction of the tenant has been instituted), the landlord may apply to the prescribed authority for his eviction under section 21, and thereupon the prescribed authority shall order the eviction of the tenant from the building under tenancy, and it shall not be necessary for prescribed authority to satisfy itself afresh as to the existence of any ground as aforesaid, and such order shall be final and shall not be open to appeal under section 22: Provided that no application under this clause shall be maintainable on the basis of a permission granted under section 3 of the old Act, where such permission became final more than three years before the commencement of this Act: Provided further that in computing the period of three years, the time during which the applicant has been prosecuting with due diligence any civil proceeding whether in a court of first instance or appeal or revision shall be excluded" All these aspects were considered by the High Court.