I deal with the claim on contract first. The warranty relied on is an undertaking by the appellant that the Bohemia Theatre would not during the currency of the lease be used as a theatre or in opposition to the Cremorne Theatre. It is necessary to remember that the respondents have to establish an agreement to that effect, which, "not being an essential part of the contract either intrinsically or by agreement, is collateral to the main purpose of" the contracts referred to (Dawsons Ltd v Bonnin[1]). It is also to be borne in mind that any words amounting to a representation or assertion as to an event, present or future, if they appear either expressly or inferentially to have been given and acted on as an acceptance of responsibility in case the representation or assertion proves untrue, are sufficient to constitute a warranty (Schawel v Reade[2]; Heilbut, Symons & Co v Buckleton[3]). The point at issue is whether such a warranty has been established. That the question is by no means easy of determination is shown by the hesitancy felt by the learned primary Judge (Dixon A.J.) and by the division of opinion in the Full Court of Victoria. I have arrived at the conclusion that the respondents have failed to maintain the case set up, by reason of two circumstances, or, perhaps, of the combination of two circumstances. The first is the opinion of the learned primary Judge. I do not regard his opinion as based on a bald rejection of the relevant testimony that supported respondents' case. Such a rejection would have been the end of the matter, and there would have been no ground for his hesitation. There is consequently room for the appellate Court to form its own estimate. But in forming its estimate as to whether the communings of the parties amounted to a giving and taking of the appellant's responsibility in case the Bohemia Theatre was used as an opposition theatre, some weight at least must be given to the way in which the evidence was given and the impression it conveyed to the presiding Judge. Mr. Hogan, however, contended that the circumstances were so strong as to overcome that advantage of the primary tribunal, and to entitle the respondents to maintain the judgment of the Supreme Court. This brings in the second circumstance that influences me. I recognize at once that all three members of the Full Court thought that the appellant had given a promise which would in itself be sufficient to constitute a warranty. It is not, of course, disputed that the majority (Irvine C.J. and Cussen J.) so held. But also McArthur J. so considered. Speaking of the third proposal made during the negotiations with respect to Bohemia, the learned Judge said: "Thirdly, that Bohemia should (if opportunity occurred) be let as a shop or garage - or for some purpose which would not bring it into opposition with Cremorne - and that the rent received for Bohemia should be applied in reduction of the rent of Cremorne." As to this purpose, McArthur J. thus states his conclusion: - "The last proposal was assented to, and the effect of it was - and was, I think, intended to be - not only that Cremorne should get the advantage of any rent received for Bohemia, but that the defendant should (by necessary implication) be under an obligation to retain the lease of Bohemia, so that it would be available for letting if opportunity occurred. And the effect of this no doubt would be that Bohemia would not be used in opposition to Cremorne." It is therefore clear that the Full Court thought the evidence was sufficient to establish the necessary promise. Their Honors diverged, however, at a point. The majority thought the promise was intended as collateral, and could stand without incorporation into the main contract; the minority thought the promise was intended to be essential and to be matter for rectification. I do not stop to inquire what course my own mind would take if I reached the same point as their Honors, namely, that the necessary promise had been made. That is to say, I do not express any opinion as to whether, having found the necessary materials for doing justice, I should think the evidence compelled me to delay that justice and to remit the parties to further cumbersome litigation, or whether it would have justified me in agreeing with the answer of the majority to the second question propounded in the judgment of Cussen J. But I am not able to reach that point. On principle the evidence is not satisfactory. In Heilbut, Symons & Co v Buckleton[4] Lord Moulton, with the approval of Lord Haldane L.C., said: - "Such collateral contracts, the sole effect of which is to vary or add to the terms of the principal contract, are therefore viewed with suspicion by the law. They must be proved strictly. Not only the terms of such contracts but the existence of an animus contrahendi on the part of all the parties to them must be clearly shown." The only testimony adduced for the purpose is oral. The inferiority of oral evidence for the purpose is recognized in Jacobs v Batavia and General Plantations Trust[5]. The difficulty is enhanced by the nature of the case. The warranty alleged is really a variation of the written contract of lease. The clause in that contract relating to the deduction of rent if the Bohemia Theatre be let, does not restrict the purpose for which the lessor might let it. There is, no doubt, an implied covenant by the lessor that he will not disable himself from carrying out the promise therein expressed, but the promise does not limit the scope of his letting. I do not agree with the contention that the construction of the clause is to be altered by reason of the negotiations. That would be a fundamental error. The warranty therefore varies the right of the lessor as that would exist under the contract. The presumption is strong that a written contract is the conclusive record of the agreement of the parties with respect to its subject matter, and consequently that it is the exclusive evidence of that agreement. The more formal, precise and detailed the written contract, the stronger is the presumption and the more difficult to overcome by oral testimony. I regard it as a highly dangerous course for a Court to take, to sanction the virtual variation of written contracts, and even contracts under seal, by controverted oral evidence, unless supported by circumstances of the clearest and most convincing character.