oilfield etc. to which the Act applies, from the operation of the provisions of the Act if, in the opinion of the appropriate Government, the employees in such establishment, factory, mine etc. are in receipt of gratuity or pensionary benefits not less favourable than the benefits conferred under the Act. In these writ petitions, it is not in dispute that the employees were originally appointed in the Board and later they were allotted to the petitioner Corporation, which was constituted pursuant to the provisions under the A.P. Electricity Reforms Act, 1998. During the year 1995, on the application made by the erstwhile Board, the Government has issued G.O.Ms.No.51, dated 18.12.1994, exempting all the employees of the Board who are governed by the Andhra Pradesh State Electricity Board Liberalised Pension Rules including Death-cum-Retirement Gratuity Benefit, from the purview of all the provisions of the Act and the Rules made thereunder. It is true that there was amendment to Section 4(3) of the Act, but when the exemption granted under G.O.Ms.No.51, dated 18.12.1995 was in force, the employees of the erstwhile Board were outside the purview of the Act. Though it is the case of the employees that by virtue of the amendment made to Section 4 (3) of the Act, G.O.Ms.No.51, dated 18.12.1995 would become inoperative, in view of the said G.O. being not challenged, it is not open to the employees to go into the validity of the said G.O. in these writ petitions.