17. The submission of learned counsel for the petitioners that there was no conscious decision taken to do away with the age relaxation granted vide notification dated 01.11.1980, after the making of the Rules of 2011, also has no merit. This is for the reason that the Rules of 2011 have been made by the Hon’ble Lt. Governor of NCT of Delhi himself in exercise of powers conferred by proviso to Article 309 of the Constitution of India. There is a presumption of validity attached to official acts, and it was for the petitioners to rebut the same by producing cogent material. The petitioners, apart from claiming that there was no conscious decision taken by the Hon’ble Lt. Governor, not to apply the notification dated 01.11.1980 in respect of recruitment of PETs under the Rules of 2011, has not produced any material in support of the said plea. On the other hand, the respondents, in their counter affidavit before the Tribunal have specifically averred that while amending the recruitment rules for PET, vide Rules of 2011, the notification dated 01.11.1980 had been taken into account and that the Recruitment Rules for PET had been amended in consultation with the UPSC and that they were as per the DoPT norms.