JUDGMENT M.H. Beg, J. - This is a plaintiff's appeal arising out of a suit for the eviction of the defendants-respondents after obtaining the permission of the Rent Control and Eviction Officer of Basti filed in 1952. The plaintiff-appellant has been wanting to reconstruct his house, and he accordingly, obtained the permission of the Rent Control and Eviction Officer who was said to be the duly authorised officer for the purpose of obtaining the permission and filed his suit for the eviction of the defendants-respondents from the accommodation in dispute. A number of pleas were taken by the defendants-respondents but they were decided against them. The only question which remained for decision was whether the District Magistrate of Basti had duly authorised the Rent Control and Eviction Officer under Section 2(d) of the U.P. (Temporary) Control of Rent and Eviction Act III of 1947 (hereinafter referred to as the Act) which runs as follows:- "District Magistrate includes an officer authorised by the District Magistrate to perform any of his functions under this Act". This question was decided by the trial court in favour of the plaintiff-appellant on 14.12.61 after the case had been remanded for trial of this issue alone by the lower appellate court which had set aside the decree for ejectment of the defendants-respondents on the ground that the above-mentioned question ought to have formed the subject-matter of a separate issue. The defendants-respondents appealed for the second time after the second decree for ejectment against them. He succeeded in the lower appellate court which allowed the appeal of the defendants-respondents on the ground that the trial court had relied upon inadmissible evidence and irrelevant facts in holding that the power of the District Magistrate had been delegated to the Rent Control and Eviction Officer. Hence, the plaintiff's second appeal to this Court. *** 4. The real reason for the failure of the lower appellate court to consider all the above mentioned evidence of authorisation of the Rent Control and Eviction Officer by the District Magistrate under Section 2 (d) of the Act, appears to be that it assumed that such an authorisation could only be proved if it was written. After assuming that, it went on to hold that, as the original had not been forthcoming, the only kind of secondary evidence which was legally admissible to prove its contents was a certified copy. After assuming that, it went on to hold that, as the original had not been forthcoming, the only kind of secondary evidence which was legally admissible to prove its contents was a certified copy. It held that Section 65 Clause (e) of the Indian Evidence Act debarred the production of any other secondary evidence in such a case. Evidently, the lower appellate court was of opinion that the original authorisation was in the form of a document which was a public document within meaning of Section 74 of the Indian Evidence Act. 5. It is true that Section 65 provides that "in case (e) or (f) a certified copy of the document, but no other kind of secondary evidence, is admissible." But Section 65 (e) of the Indian Evidence Act could only apply where the original is a public document in existence. It could not apply to a case in which the public document is not proved to be any longer in existence or one which having been lost, is as good as a document which is no longer is existence. It has not been shown to me that the order of the District Magistrate authorising a Rent Control and Eviction Officer under Section 2(d) of the U.P. Act, is a document of which a certified copy is to be given under any law. Moreover, no certified copy can be obtained where the document itself has disappeared. The reason why certified copies of public documents are permitted and given is that the public document may not be lost or damaged, and another reason is that a certified copy is a very reliable kind of proof of the contents of the original. The reason why other kinds of secondary evidence, except certified copies, is excluded is that the best available evidence must be given. Now where the original itself has vanished, it is not possible to obtain a certified copy of it. If a certified copy cannot be obtained at all it ceases to be best evidence. In my opinion, best evidence means only best available evidence. It could not mean evidence which ought to have been or may have been available. I am, therefore, of opinion that the existence of a public document must be proved before the provision excluding every other kind of secondary evidence of it except a certified copy is applied. In my opinion, best evidence means only best available evidence. It could not mean evidence which ought to have been or may have been available. I am, therefore, of opinion that the existence of a public document must be proved before the provision excluding every other kind of secondary evidence of it except a certified copy is applied. If a public document has disappeared from the relevant records, as is the position in this case, it no longer forms either an act or a record of the act. Section 65(e) of the Indian Evidence Act also postulates that there "is" a public document, or, in other words, the document exists. As soon as Cls. (e) and (f) of Section 65 of the Indian Evidence Act cease to apply to a case, because the document in question has disappeared, evidence of that document will become admissible under Clause (c) of Section 65. This view is supported by the following cases: C. Veerasetty v. Nanjunda Chari A.I.R. 1955 Mys. 139, Kalandan v. Kunhunni I.L.R. 6 Mad. 80, H.C. Mullick v. P.C. Bannerji 22 Suth WR. 303, A.K. Bhattacharji v. Secretary of State I.L.R. 43 Cal. 973 and C.P.N. Singh v. B.P.N. Singh A.I.R. 1927 Pat. 61. No authority has been shewn to me in which a contrary view has been taken. I, therefore, hold that the lower appellate court erred in excluding secondary evidence of authorisation of the Rent Control and Eviction Officer which was admissible under the law. 6. It is not necessary for an authorisation by the District Magistrate, in favour of a Rent Control and Eviction Officer under Section 2(d) of the U.P. Act III of 1947, to be either in writing or in any particular form. I may, however, point out that even where a public officer is required by law to be appointed in writing, a presumption arises, from the fact that he has so acted, that he has been duly appointed (vide exception 1 to Section 91 of the Evidence Act). In the present case it is only due authorisation and not appointment which has to be presumed. I have no doubt whatsoever that the fact that the Rent Control and Eviction Officer acted in a particular capacity and discharged the functions of the District Magistrate by granting a permission, would be enough to raise a presumption under Section 114 (e) of the Indian Evidence Act. I have no doubt whatsoever that the fact that the Rent Control and Eviction Officer acted in a particular capacity and discharged the functions of the District Magistrate by granting a permission, would be enough to raise a presumption under Section 114 (e) of the Indian Evidence Act. In M.A. Rafiq v. Smt. Maya Devi, 1963 A.L.J. 82, it has been held by this Court that the initial burden of proving that a suit has been filed with a valid permission given to a landlord would be discharged by producing the order granting permission. After that, the burden would shift to the shoulders of the defendant if he still denies that the officer granting permission had no authority to grant it. In the present case, a certified copy of the Rent Control and Eviction Officer was filed by the plaintiff, who also led the other evidence mentioned above, but, the defendants-respondents led no evidence whatsoever to disprove the assertion that the officer concerned had the requisite authority. On this matter also the lower appellate court has, in my opinion, clearly erred. 7. The lower appellate court has also, in my opinion, erred in not relying upon the principle of estoppel against the defendants respondents. If the defendants-respondents had proved that he was labouring under some mis-apprehension as a result of which he could not take the plea of absence of authority of the Rent Control and Eviction Officer, when he appeared before that officer and submitted to his jurisdiction, he may have ben able to show some justification for avoiding the application of the equitable principle of estoppel against him. Again, if the defendants-respondents had clearly proved that the Rent Control and Eviction Officer could not possibly have had any authority under the law to grant permission he may have been able to avoid an estoppel against law. If, for example, the U.P. Act III of 1947 had lodged the authority to grant permission in the District Magistrate exclusively, without any provision for delegating that authority to other officers, the defendants-respondents could have, even though they submitted to the jurisdiction of the officer concerned, turned round and denied his authority on the ground that there is no estoppel against statute. But, the facts of the present case are distinguishable. But, the facts of the present case are distinguishable. In my opinion, the defendants-respondents were under the duty to speak and to object to the jurisdiction of the officer concerned when they appeared before him. If they failed to perform that duty and mislead the plaintiff-appellant who has, as a result of that failure, incurred expense and spent time and undergone trouble in litigating, the elements of an estoppel are made out against the defendants-respondents. 8. In the result, I allow this appeal and set aside the judgment and decree of the lower appellate court and restore that of the trial court. The plaintiff's suit for ejectment of the defendants shall stand decreed with costs throughout.