8. In his written case counsel for Capita argued that the Court of Appeal had fallen into error because it had been influenced by a submission by Mr Wood's counsel that the decision of this court in Arnold v Britton [2015] AC 1619 had "rowed back" from the guidance on contractual interpretation which this court gave in Rainy Sky SA v Kookmin Bank [2011] 1 WLR 2900. This, he submitted, had caused the Court of Appeal to place too much emphasis on the words of the SPA and to give insufficient weight to the factual matrix. He did not have the opportunity to develop this argument as the court stated that it did not accept the proposition that Arnold had altered the guidance given in Rainy Sky. The court invited him to present his case without having to refer to the well-known authorities on contractual interpretation, with which it was and is familiar.
9. It is not appropriate in this case to reformulate the guidance given in Rainy Sky and Arnold; the legal profession has sufficient judicial statements of this nature. But it may assist if I explain briefly why I do not accept the proposition that Arnold involved a recalibration of the approach summarised in Rainy Sky.
10. The court's task is to ascertain the objective meaning of the language which the parties have chosen to express their agreement. It has long been accepted that this is not a literalist exercise focused solely on a parsing on the wording of the particular clause but that the court must consider the contract as a whole and, depending on the nature formality and quality of drafting of the contract, give more or less weight to elements of the wider context in reaching its view as to that objective meaning. In Prenn v Simmonds [1971] 1 WLR 1381 (1383H-1385D) and in Reardon Smith Line Ltd v Yngvar Hansen-Tangen [1976] 1 WLR 989 (997), Lord Wilberforce affirmed the potential relevance to the task of interpreting the partie's contract of the factual background known to the parties at or before the date of the contract, excluding evidence of the prior negotiations. When in his celebrated judgment in Investors Compensations Scheme Ltd v West Bromwhich Building Society [1998] 1 WLR 896 Lord Hoffmann (pp 912-913) reformulated the principles of contractual interpretation, some saw his second principle, which allowed consideration of the whole relevant factual background available to the parties at the time of the contract, as signalling a break with the past. But Lord Bingham in an extra-judicial writing, A new thing under the sun? The interpretation of contracts and the ICS decision Edin LR Vol 12, 374-390, persuasively demonstrated that the idea of the court putting itself in the shoes of the contracting parties had a long pedigree.
11. Lord Clarke elegantly summarised the approach to construction in Rainy Sky at para 21f. In Arnold all of the judgments confirmed the approach in Rainy Sky (Lord Neuberger paras 13-14; Lord Hodge para 76; and Lord Carnwath para 108). Interpretation is, as Lord Clarke stated in Rainy Sky (para 21), a unitary exercise; where there are rival meanings, the court can give weight to implications of rival constructions by reaching a view as to which construction is more consistent with business common sense. But, in striking a balance between the indications given by the language and the implications of the competing constructions the court must consider the quality of drafting of the clause (Rainy Sky para 26, citing Mance LJ in Gan Insurance Co Ltd v Tai Ping Insurance Co Ltd (No 2) [2001] 2 All ER (Comm) 299 paras 13 and 16); and it must also be alive to the possibility that one side may have agreed to something which with hindsight did not serve his interest: Arnold (paras 20 and 77). Similarly, the court must not lose sight of the possibility that a provision may be negotiated compromise or that the negotiators were not able to agree more precise terms.
12. This unitary exercise involves an interative process by which each suggested interpretation is checked against the provisions of the contract and its commercial consequences are investigated: Arnold para 77 citing In re Sigma Finance Corpn [2010] 1 All ER 571, para 10 per Lord Mance. To my mind once one has read the language dispute and the relevant parts of the contract that provide its context, it does not matter whether the more detailed analysis commences with the factual background and the implications of rival construction or a close examination of the relevant language in the contract, so long as the court balances the indications given by each.
13. Textualism and contextualism are not conflicting paradigms in a battle for exclusive occupation of the field of contractual interpretation. Rather, the lawyer and the judge, when interpreting any contract, can use them as tools to ascertain the objective meaning of the language which the parties have chosen to express their aggreement. The extent to which each tool will assist the court in its task will vary according to the circumstances of the particular agreement or agreements. Some agreements may be successfully interpreted principally by textual analysis, for example because of their sophistication and complexity and because they have been negotiated and prepared with the assistance of skilled professionals. The correct interpretation of other contracts may be achieved by a greater emphasis on the factual matrix, for example because of their informality, brevity or the absence of skilled professional assistance. But negotiators of complex formal contracts may often not achieve a logical and coherent text because of, for example, the conflicting aims of the parties, failures of communication, differing drafting practices, or deadlines which require the parties to compromise in order to reach agreement. They may often therefore be provisions in a detailed professionally drawn contract which lack clarity and the lawyer or judge in interpreting such provisions may be particularly helped by considering the factual matrix and the purpose of similar provisions in contracts of the same type. The iterative process, of which Lord Mance spoke in Sigma Finance Corpn (above), assists the lawyer or judge to ascertain the objective meaning of disputed provisions.
14. On the approach to contractual interpretation, Rainy Sky and Arnold were saying the same thing.
15. The recent history of the common law of contractual interpretation is one of continuity rather than change. One of the attractions of English law as a legal system of choice in commercial matters is its stability and continuity, particularly in contractual interpretation.