Patel v. Union of India (2012) 7 SCC 757, where it was held that a person who has applied for an appointment on deputation, “has an indefeasible right to be treated fairly and equally and once such person is selected and offered a letter of appointment on deputation, the same cannot be cancelled except on the ground of non-suitability or unsatisfactory work.” Reliance was also placed on the decision in S.I. Rooplal v. The Lt. Governor through the Chief Secretary, Delhi AIR 2000 SC 594, which recognised the right of the deputationist to count the substantive service rendered by him in the parent cadre. As regards the belated challenge to the gradation list, reliance was placed on the decision in S. Sumnyan v. Limi Nini AIR 2010 SC 2159. Reference was also made to the decisions in Harshit Agarwal v. Union of India (2021) 2 SCC 710 ; Kendriya Vidyalaya Sangathan v. Sajal Kumar Roy (2006) 8 SCC 671 and Ashok Kumar Sonkar v. Union of India (2007) 3 Supreme 956 to urge