“[16] … The court has no power to improve upon the instrument which it is called upon to construe, whether it be a contract, a statute or articles of association. It cannot introduce terms to make it fairer or more reasonable. It is concerned only to discover what the instrument means. However, that meaning is not necessarily or always what the authors or parties to the document would have intended. It is the meaning which the instrument would convey to a reasonable person having all the background knowledge which would reasonably be available to the audience to whom the instrument is addressed: see Investors Compensation Scheme Ltd v West Bromwich Building Society[1998] 1 WLR 896 , 912–913. It is this objective meaning which is conventionally called the intention of the parties, or the intention of Parliament, or the intention of whatever person or body was or is deemed to have been the author of the instrument. [17] The question of implication arises when the instrument does not expressly provide for what is to happen when some event occurs. The most usual inference in such a case is that nothing is to happen. If the parties had intended something to happen, the instrument would have said so. Otherwise, the express provisions of the instrument are to continue to operate undisturbed. If the event has caused loss to one or other of the parties, the loss lies where it falls.”
“[18] In some cases, however, the reasonable addressee would understand the instrument to mean something else. He would consider that the only meaning consistent with the other provisions of the instrument, read against the relevant background, is that something is to happen. The event in question is to affect the rights of the parties. The instrument may not have expressly said so, but this is what it must mean. In such a case, it is said that the court implies a term as to what will happen if the event in question occurs. But the implication of the term is not an addition to the instrument. It only spells out what the instrument means. … [21] It follows that in every case in which it is said that some provision ought to be implied in an instrument, the question for the court is whether such a provision would spell out in express words what the instrument, read against the relevant background, would reasonably be understood to mean. It will be noticed from Lord Pearson's speech [in Trollope & Colls Ltd v North West Metropolitan Regional Hospital Board[1973] 1 WLR 609 ] that this question can be reformulated in various ways which a court may find helpful in providing an answer – the implied term must “go without saying”, it must be “necessary to give business efficacy to the contract” and so on – but these are not in the Board's opinion to be treated as different or additional tests. There is only one question: is that what the instrument, read as a whole against the relevant background, would reasonably be understood to mean?”
“(1) it must be reasonable and equitable; (2) it must be necessary to give business efficacy to the contract, so that no term will be implied if the contract is effective without it; (3) it must be so obvious that ‘it goes without saying’ (4) it must be capable of clear expression; (5) it must not contradict any express term of the contract.” [27] The Board considers that this list is best regarded, not as series of independent tests which must each be surmounted, but rather as a collection of different ways in which judges have tried to express the central idea that the proposed implied term must spell out what the contract actually means, or in which they have explained why they did not think that it did so. The Board has already discussed the significance of ‘necessary to give business efficacy’ and ‘goes without saying’. As for the other formulations, the fact that the proposed implied term would be inequitable or unreasonable, or contradict what the parties have expressly said, or is incapable of clear expression, are all good reasons for saying that a reasonable man would not have understood that to be what the instrument meant.” “(1) it must be reasonable and equitable; (2) it must be necessary to give business efficacy to the contract, so that no term will be implied if the contract is effective without it; (3) it must be so obvious that ‘it goes without saying’ (4) it must be capable of clear expression; (5) it must not contradict any express term of the contract.”
“In this case the substance of the misrepresentation by the defendants, as alleged by the plaintiffs, is fairly capable of being expressed thus: ‘If you order a conservatory from us you will be getting a conservatory designed, manufactured and constructed by the people who have earned the goodwill and reputation that properly belongs to the party which secured the orders and designed, manufactured and constructed the conservatories shown in these photographs. The conservatories shown in the photographs indicate the skill, the experience and the reputation of the party who designed and made them. That party is Custom Built.’ But, of course, it was not.”