JUDGMENT S.H.A. Raza, J. - The main question involved in this writ petition is as to whether the seniority of the petitioners deserves to be determined from the date of their substantive appointment as Physical Training Instructor or from the date when their services were merged into the Trained Graduate Grades with effect from the Government order dated 22-9-1977. 2. The main contention of the petitioners is that while determining the seniority of The petitioners, the opposite parties have taken the date 22-9-77 as the date of appointment by ignoring the total length of service, in spite of the fact that the Government order by means of which the petitioner's cadre was brought into the general cadre did not provide that the seniority of the petitioner would be fixed by treating 22-9-77 i.e. date of merger, as the date of appointment. In this connection it is necessary to mention that by the Government order Education (2) Anubhag Sankhya 519Ka/15(2)-3(6)/117/98, dated September 22, 1977, which has been annexed as Annexure No. 3 to the writ petition, provided that from the date of the issue of the said order C.T. and L.T. grade teachers working in Arts, and Crafts, Physical Training and Music will be merged in C.T. and L.T. Grade, thereafter they would be deemed to be teachers appointed in the general grade. It is pertinent to mention here that this order does not indicate as to whether their seniority would be determined from the date of their respective appointment as instructors of physical education or from the date of their merger with the general cadre of teachers working in C.T. grade either temporarily or permanently. 3. On 5-1-81 the Government of U.P. issued another order addressed to the Director of Education, U.P , Allahabad, pertaining to determination of the seniority of those teachers whose services were merged in the year 1977 with the teachers of general grade. This order which has been annexed as annexure-17 to the writ petition indicates that although the policy decision regarding the determination of seniority of the aforesaid teachers was taken by the State Government on 6-12-71 and Government orders were issued but the confusion still persisted which might cause irregularities, hence it required further clarification. This order which has been annexed as annexure-17 to the writ petition indicates that although the policy decision regarding the determination of seniority of the aforesaid teachers was taken by the State Government on 6-12-71 and Government orders were issued but the confusion still persisted which might cause irregularities, hence it required further clarification. Sri Vinai Krishna, Deputy Secretary, Government of U.P., in the said Government order stated that he had been directed to clarify that as a result of merger of the teachers who were appointed as teachers in Arts and Crafts, Physical Education and Music, respectively, in C.T. and L.T. grade into general cadre of teachers, their seniority vis-a-vis with general grade teachers would be determined with effect from the date of their substantive appointment to the post. The said order further clarified that substantive appointment meant that the appointment which was regularly sanctioned by the government, whether the post was temporary or permanent. It further clarified that substantive appointment meant appointment on substantive vacancy filled in regular manner, meaning thereby that the appointment was regularly made by a proper selection procedure, whether the appointment was temporary or permanent. 4. The aforesaid order further clarified that those teachers falling in general category who had been promoted prior to 21-9-77 on the basis of their seniority already determined would not be reverted on the basis of the aforesaid policy. Thus it is clear that in the aforesaid Government order inter se seniority of the teachers, whether they were initially appointed as teachers of Arts & Crafts, Physical Training and Music or teachers of the general category was determined on the basis of length of their service i.e. from the date of their substantive appointment on the posts. 5. It seems that thereafter on 8-1-85 the Government of U.P. published another seniority list, in which the date of appointment of the petitioners, who were appointed as Physical Training Instructors, had been treated to be the date of merger in the general cadre i.e. 22-9-77. The petitioners challenged the aforesaid seniority list by making representations to the authorities concerned. 5. It seems that thereafter on 8-1-85 the Government of U.P. published another seniority list, in which the date of appointment of the petitioners, who were appointed as Physical Training Instructors, had been treated to be the date of merger in the general cadre i.e. 22-9-77. The petitioners challenged the aforesaid seniority list by making representations to the authorities concerned. The said seniority list had been challenged on the ground that it could not be said to be the tentative seniority list or final seniority list in which the date of the appointment of the petitioners had been published as 22-9-77 on which date the petitioners cadre was brought into the general cadre i.e. L.T. Grade as a result of which petitioner no. 1 had been placed at Serial No. 548, petitioner no. 2 at serial no. 544 and the petitioner no. 3 at serial no. 546. 6. The main thrust of the argument of the learned counsel for the petitioner in challenging the said tentative seniority list is that while determining the seniority of the petitioners the opposite parties have taken the date 22-9-77 as the date of appointment by ignoring the total length of service, which they cannot do. Even the Government order by means of witch the petitioners' ex-cadre post was brought into general cadre post, does not provide that the seniority of the petitioners would be fixed by treating 22-9-77 i.e. the dale of merger as the date of appointment, it was averred that the petitioners were selected and appointed by the Public Service Commission. The petitioner no. 1 was appointed on 14-12-62 and was given substantive appointment on 31-12-64 and was confirmed with effect from 31-12-64 vide order dated 16-1-74. The petitioner no. 2 was appointed on 9-11-62 and he joined his duties on 22-11-62 and he was given substantive appointment with effect from 14-9-66 and was confirmed with effect from 14-9-66 vide order dated 17-1-74 whereas the petitioner no. 3 was selected and appointed on 9-11-62 and was given substantive appointment with effect from 16-9-64 and he was confirmed with effect from 14-9-66. Thus, while determining the seniority the aforesaid dates ought to have been taken into consideration i.e. the initial date of appointment, and not the date of merger in the general cadre i.e. 22-9-77. 3 was selected and appointed on 9-11-62 and was given substantive appointment with effect from 16-9-64 and he was confirmed with effect from 14-9-66. Thus, while determining the seniority the aforesaid dates ought to have been taken into consideration i.e. the initial date of appointment, and not the date of merger in the general cadre i.e. 22-9-77. The State Government has also issued a Government Order in the year 1982 providing therein that while determining the seniority, initial date of appointment as Assistant Teachers shall be taken into consideration and the total length of service shall be taken for determining the seniority. 7. From the side of the opposite parties, counter affidavit was filed on 24-7-90 in which it was alleged that the seniority list as published on 18-8-81 had already been cancelled and subsequently a tentative list dated 14-3-88 had been published against which objections had been invited and the same was in process of finalisation. In view of the aforesaid facts the directions issued by this court on interim matter to promote the petitioners in accordance with the seniority list dated 18-8-81 which was non-existent was not possible to be complied with. It was further submitted in this counter affidavit as well as in detailed counter affidavit which is already on record that the petitioner belonged to an ex-cadre category and they have been cadred with the general teachers only 22-9-77 by virtue of the amalgamation of their services. Thus the petitioners would be assigned their seniority in the general cadre i.e. with effect from 22-9-77. 8. A perusal of the affidavit filed by the parties would indicate that in the tentative seniority list issued in the year 1981 the seniority of the petitioners was determined considering the length of their service. The Government of U.P. in the Government order contained in annexure-7 also indicated that seniority of both cadres would be determined with effect from the date of the substantive appointment but this policy underwent a complete change and another seniority list was published on 14-3-88 which provided that C.T./L.T. grade teachers in general category even after amalgamation of service on 21-9-77 shall be senior to those whose services were merged by means of the Government order dated 22-9-77 with the general cadre, who were working in C.T./L.T. grade but were not in the cadre of L.T. grade teachers till 21-9-77. In other words their date of appointment would be 22-9-77. Hence all those teachers in the general category who were working till 21-9-77 would be senior and the teachers who were initially appointed as teachers of Arts and Crafts, Physical Education and Music on or after 22-9-77 shall become junior. 9. Normally an ex-cadre post means a post outside the one comprised in service. Admittedly the petitioners were also appointed as teachers of physical Education and there existed another type of teachers who were appointed in general grade, although undoubtedly both were recruited for imparting education, it may be that one category of teachers was appointed to instruct the students in Physical Education, Music, and Arts and Crafts while the other set of teachers were recruited to impart education on the subject of humanities, science and commerce etc. There may be different categories or grades but it cannot be said that the petitioners who were recruited for imparting education on the subject of Physical Training etc. belonged to an ex-cadre post. After the recruitment they were promoted as lecturers in L.T. grade and by means of order dated 22-9-77 their services were merged into general grade teachers. The order did not indicate as to how their seniority would be determined, but by means of Government order dated 5-1-81 it was clarified that inter se seniority of the petitioners vis-a-vis general grade teachers would be determined from the date of their substantive appointment. The tentative seniority list of 1981 also provided that the seniority of the petitioners would be determined from the date of their substantive appointment. Now it does not lie in the mouth of the opposite parties to bid a good bye to earlier Government orders, as such the impugned order would be barred by principles of promissory estoppel. 10. If it is assumed that the petitioner's post was an ex-cadre post, even then after the amalgamation of their services, with the general category and the decision of the Government that their seniority would be determined from the date of their substantive appointment, cannot be altered or changed in an arbitrary manner. 11. The principle for deciding the interse seniority must conform with the principles of equality spelt out by Articles 14 and 16 of the Constitution of India. 11. The principle for deciding the interse seniority must conform with the principles of equality spelt out by Articles 14 and 16 of the Constitution of India. The teachers of both the grade cannot be treated to be unequal as one set of teachers was appointed to give instructions of Physical Training, Music and Arts and Craft and the other set of teachers was appointed to impart education to the students on the subject of humanities, commerce and science etc. In the case of S.B. Patwardhan v. State of Maharashtra (1977) 3 SCR., 375, the persons who were promoted and who were directly recruited were held to be belonging to the same cadre. The said judgment was relied upon by the Hon'ble Supreme Court in the case of Direct recruits Class II Engineering Officers Association v. State of Maharashtra and others (Civil Appeals No. 194 to 202 of 1986 decided on May 2, 1990 (1990(8) LCD 449) in which it was laid down that the decision dealing important questions concerning with a particular service given after careful consideration should be accepted rather than scrutinised for finding out any possible error. It is not in the interest of service to unsettle the settled position. In the instant case the settled position since 1981 to 1988 was that the seniority of the petitioners would be determined from the date of their substantive appointment on the post. This settled position was unsettled only by means of the Government order dated 14-3-88 which had been challenged in this writ petition. 12. In the case of Nityananda Ker v. State of Orissa, reported in 1991(62) FLR 145 their lordships of the Supreme Court dealing with the inter se seniority between the direct recruits and the mergerists of the two services into one single cadre known as OAS II held that the principle followed continuously and traditionally for decades in service of state shall not be challenged vicariously. Relying upon the case of Anant Kumar Bose v. State of Orissa, reported in AIR 1986 Orissa 151 their lordships held that: "The accepted and continued position was strangely being upset when direct recruits of 1972 had acquired a vested right to be ranked senior to the mergerists. Relying upon the case of Anant Kumar Bose v. State of Orissa, reported in AIR 1986 Orissa 151 their lordships held that: "The accepted and continued position was strangely being upset when direct recruits of 1972 had acquired a vested right to be ranked senior to the mergerists. Though it is true that vested rights can also be taken away by an Act of legislature and it can be assumed that the legislature knew the subject it was dealing with, yet, in the instant case we are of the view that when complete integration of the two services of O.A.S. III and O.A.S. II had been brought about on December 21, 1973, without repeal of the recruitment rules of 1959, there was nothing to classify or differentiate between direct recruits of the year 1970 & 1971 on the one hand and the direct recruits of the year 1972 on the other. Since the two groups of recruits were similarly placed and the situation did not yield to any reasonable classification it was not open to the State Legislature to maintain an artificial classification and provide by the impugned Act unequal treatment to the 1972 recruits. Thus we declare Section 3(2)(a) of the Validation Act insofar as it permits the deemed promotes of the year" 1972 to be placed above the direct recruits of the year 1972 in the Gradation List, as violative of Article 14." Summing up the question their lordships further indicated as under : "Thus to sum up, we hold that Ananta Kumar Bose's case (supra) is the binding decision as approved by this Court on the important questions dealt therein and the foundation laid concerning integration of both the services of O.A.S. II and O.A.S. III as merged in O.A.S. II and we decline to unsettle a sett led position in the interest of the service. We accordingly dismiss Civil Appeal No. 750 of 1987 and also Writ Petition No. 12770/85 and to that extent Writ Petition No. 1044/87 on that point. We have, however, allowed the later writ petition in part to the extent above indicated of declaring Section 3(2)(a) ultra vires of Article 14 of the Constitution and extend the benefit of Ananta Kumar Bose's case (supra) to the 1972 direct recruits as well. For the reasons indicated we have not made any final order on merit in W.P. 929 of 1987. For the reasons indicated we have not made any final order on merit in W.P. 929 of 1987. In the facts and circumstances of the case, however, we leave the parties to bear their own costs." 13. In view of what has been indicated herein above the writ petition is allowed and a writ in the nature of certiorari is issued quashing the seniority list dated 14-3-88 contained in Annexure-14 of the writ petition pertaining to the petitioners. A writ in the nature of mandamus is also issued commanding the opposite parties to determine the seniority of the petitioners in the light of the observations made above, consider the case of the petitioner for promotion prior to 1984 and decide the representation preferred by the petitioners against the seniority list published on 14-3-88 contained in annexure-14, as indicated herein above, within six weeks from the date of the production of a copy of this order by the petitioners to the opposite parties.