… what the court must do must be to place itself in thought in the same factual matrix as that in which the parties were. All of these opinions seem to me implicitly to recognise that, in the search for the relevant background, there may be facts which form part of the circumstances in which the parties contract in which one, or both, may take no particular interest, their minds being addressed to or concentrated on other facts so that if asked they would assert that they did not have these facts in the forefront of their mind, but that will not prevent those facts from forming part of an objective setting in which the contract is to be construed."
29 These passages, together with the passage in the judgment of Stephen, Mason and Jacobs JJ in DTR Nominees Pty Ltd v Mona Homes Pty Ltd [1978] HCA 12; 138 CLR 423 at 429 which referred to the "mutually known facts", were the foundations of the views of Mason J in Codelfa Construction Pty Ltd v State Rail Authority of New South Wales [1982] HCA 24; 149 CLR 337 at 347-353, especially at 352, where his Honour said:
"Generally speaking facts existing when the contract was made will not be receivable as part of the surrounding circumstances as an aid to construction, unless they were known to both parties, although, as we have seen, if the facts are notorious knowledge of them will be presumed."
30 As Macfarlan JA pointed out in The Movie Network Channel v Optus at [99], the words "as we have seen" were clearly a reference to what Lord Wilberforce had said in Reardon Smith. What the parties knew is thus to be understood in the sense used by Lord Wilberforce and Mason J.
31 QBE and MMI relied on a passage from Lord Hoffmann's speech in Investors Compensation Scheme Limited v West Bromwich Building Society [1998] 1 WLR 896 at 912 that was cited by Gleeson CJ, Gummow and Hayne JJ in Maggbury Pty Ltd v Hafele Australia Pty Ltd [2001] HCA 70; 210 CLR 181 at 188 [11]:
"the ascertainment of the meaning which the document would convey to a reasonable person having all the background knowledge which would reasonably have been available to the parties in the situation in which they were at the time of the contract."
32 Emphasis was placed in argument on the words "would reasonably have been available to the parties". It was submitted that this phrase detached the enquiry about the surrounding circumstances from what the parties knew, entitling recourse to anything that was reasonable available. I do not think any such change was intended by their Honours in Maggbury. The importance of the deployment of the above passage from Investors Compensation in Maggbury was not to signal some departure of principle from Codelfa, but rather, to re-articulate the test (by way of emphasis and expression) from the (objective) intention of the parties, to the placement of the reasonable person in the position of the parties. That Gleeson CJ, Gummow and Hayne JJ were not intending to permit extrinsic material or surrounding facts wider than as described in Codelfa and Reardon Smith can be taken by their reference, in the same footnote as contained the reference to Investors Compensation, to Codelfa at 350-352 and to the speech of Lord Bingham of Cornhill in Bank of Credit and Commerce International SA v Ali [2001] UKHL 8; [2002] 1 AC 251 at 259 [8] where Lord Bingham said:
"8. I consider first the proper construction of this release. In construing this provision, as any other contractual provision, the object of the court is to give effect to what the contracting parties intended. To ascertain the intention of the parties the court reads the terms of the contract as a whole, giving the words used their natural and ordinary meaning in the context of the agreement, the parties' relationship and all the relevant facts surrounding the transaction so far as known to the parties . To ascertain the parties' intentions the court does not of course inquire into the parties' subjective states of mind but makes an objective judgment based on the materials already identified. The general principles summarised by Lord Hoffmann in Investors Compensation Scheme Ltd v West Bromwich Building Society [1998] 1 WLR 896, 912-913 apply in a case such as this."
(emphasis added)
33 As Macfarlan JA said in The Movie Network Channel v Optus at [105], two months after Maggbury, Gleeson CJ, Gaudron, McHugh, Gummow and Hayne JJ in Royal Botanic Gardens and Domain Trust v South Sydney City Council [2002] HCA 5; 76 ALJR 436 at 445 [39] stated unequivocally that courts in Australia should follow Codelfa until otherwise stated by the High Court. Their Honours could not have understood Maggbury itself as having departed from Codelfa and as having therefore lessened, in some way, the force and authority of Reardon Smith.
34 The authority of this aspect of Codelfa as to the nature and extent of surrounding circumstances that are admissible, and the force and influence of the speech of Lord Wilberforce in Reardon Smith thereby, can be seen restated and reinforced by later authoritative High Court decisions: Pacific Carriers Ltd v BNP Paribas [2004] HCA 35; 218 CLR 451 at 461-462 [22] where the Court (Gleeson CJ, Gummow, Hayne, Callinan and Heydon JJ) referred to Codelfa at 350, Reardon Smith at 995-996 and to the warning in Royal Botanic Gardens at 445 [39]; Zhu v Treasurer of New South Wales [2004] HCA 56; 218 CLR 530 at 559 [82] (where Gleeson CJ, Gummow, Kirby, Callinan and Heydon JJ said that the "commercial purpose - the purpose of reasonable persons in the position of TOC and the plaintiff - was relevant [citing Codelfa at 351] … [which, in turn] required attention to 'the genesis of the transaction, the background, the context, the market' in which the parties were operating, as known to both parties" citing Codelfa at 350 and Reardon Smith at 995-996); Toll (FGCT) Pty Ltd v Alphapharm Pty Ltd [2004] HCA 52; 219 CLR 165 at 178-179 [38] where Gleeson CJ, Gummow, Hayne, Callinan and Heydon JJ reiterated what had been said in Ermogenous v Greek Orthodox Community of SA Inc [2002] HCA 8; 209 CLR 95 at 105-106 [25], which had stated the importance of Codelfa at 348-353, and at 179 [40] where their Honours restated the principles by reference to Pacific Carriers at 461-462; International Air Transport Association v Ansett Australian Holdings Ltd [2008] HCA 3; 234 CLR 151 at 160 [8] where Gleeson CJ referred to the commercial purpose, genesis, background and market by reference to Codelfa at 350, Reardon Smith at 995-996 and Pacific Carriers at 462 [22] and at 174 [53] where Gummow, Hayne, Heydon, Crennan and Kiefel JJ referred to the task of construction by reference to Toll at 179 [40] which had been based on the passages from Pacific Carriers at 461-462 [22].
35 It is clear from the binding Australian authorities that the scope of the surrounding circumstances, knowledge of which is to be attributed to a reasonable person in the situation of the contracting parties (not one or some only of them), is to be understood by reference to what the parties knew in the context of their mutual dealings. As Lord Wilberforce said, this does not involve a species of constructive notice. Constructive notice implies a degree of enquiry by reference to some external standard. Just because something is available to be found does not make it relevant, if the parties did not know of it. The reasonable person may be taken to know of things that go beyond those that the parties thought to be important or those to which there was actual subjective advertence by the parties. Further, the circumstances may include such things as the legal context to the transaction, especially if a market is involved. Nevertheless, the scope of the relevant material is necessarily bounded by the objective task of the reasonable person giving meaning to the words used by the parties in the circumstances in which the contract came to be written, by reference to what the parties knew in the sense stated by Lord Wilberforce in Reardon Smith, by Mason J in Codelfa and by the the High Court in the various cases since Codelfa. This is how I read the reasons of Macfarlan JA in The Movie Network Channel v Optus, with which I agree.