"Interpretation is the ascertainment ofthe 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 ofthe contract 27.2 Whereas the Court may in other contexts decline to reach a conclusion as to the meaning of a clause in a contract, a decisive result must be reached when construing a conveyance (Lewison on the Interpretation of Contracts (5 th Edition), para 1 1.02). 27.3 To the extent that the subject matter of the conveyance cannot be identified from the conveyance itself, extrinsic evidence is admissible. In particular, topographical features present on the land at the time of the relevant conveyance is admissible as an aid to the construction of a conveyance to arrive at 'the most sensible result' (Lewison On the Interpretation of Contracts (5 th edition), para. 1 1.04) 27.4 Similarly, evidence of subsequent conduct is admissible as an aid to the construction of a conveyance if it is probative of the parties' intention at the date of the conveyance (Lewison para 11.05; Watcham v Att-Gen. of the East Africa Protectorate [1919] A.C. 533; Ali v Lane[2007] 1 P&CR 26 ). In Ali v Lane left this question open. Carnwath L.J stated at paras.36-38: "
"I would add that in principle reference to the intention of the parties means the parties to the original conveyance. Thus, in Watcham the user relied on by the Privy Council was that of the Watchamfamily, who were the beneficiaries of the original certificate. In none of the cases reviewed above was account " taken ofthe conduct ofsubsequent owners 27.5 Whilst the issue of whether acts by subsequent owners might be admissible was not decided in Ali v Lane, paragraph 11.05 of Lewison concludes as follows: "
"tend to show that in cases ofconflict or uncertainty the plan is to prevail over any verbal description. He went on to conclude that where both forms of expression are used together they tend to be "mutually stultifying 28.2 These views were considered by the Court of Appeal in Wigginton Ltd v Winster Ltd[1978] 1 WLR 1462 . That case also contained both forms of phrase and the question for the Court was whether it was necessary to have regard to evidence outside the conveyance in question on the grounds that the words of qualification reduced the reliance which could be placed upon the plan. Buckley LJ cited the passages referred to above and said (at p. 1471) that the comments of Megarry J. that the phrase "for the purposes of identification only" confined the use of the plan to determining where the land was situated were obiter. Rather, Buckley LJ concluded: ... in so far as the plan does not conflict with the parcels, I can see no reason why, because it is described as being "for identification purposes only" it should not be looked at to assist in understanding the description of the parcels. The process of identification is in fact the process ofdiscovering what land was intended to pass under the conveyance, and that is the precise purpose the plan is said to serve. Accordingly, so long as the plan does not come into conflict with anything which is explicit in the description of the parcels, the fact that it is said to be "for the purposes of identification only' does not appear to me to exclude it from consideration in solving problems which are left undecided by what is explicit in the description ofthe parcel' Bridge LJ said (at p. 1475): "