“18. In the present case, the planning authority was required by section 25 to consider whether the proposed development was in accordance with the development plan and, if not, whether material considerations justified departing from the plan. In order to carry out that exercise, the planning authority was required to proceed on the basis of what Lord Clyde described as "a proper interpretation" of the relevant provisions of the plan. We were however referred by counsel to a number of judicial dicta which were said to support the proposition that the meaning of the development plan was a matter to be determined by the planning authority: the court, it was submitted, had no role in determining the meaning of the plan unless the view taken by the planning authority could be characterised as perverse or irrational. That submission, if correct, would deprive sections 25 and 37(2) of the 1997 Act of much of their effect, and would drain the need for a "proper interpretation" of the plan of much of its meaning and purpose. It would also make little practical sense. The development plan is a carefully drafted and considered statement of policy, published in order to inform the public of the approach which will be followed by planning authorities in decision-making unless there is good reason to depart from it. It is intended to guide the behaviour of developers and planning authorities. As in other areas of administrative law, the policies which it sets out are designed to secure consistency and direction in the exercise of discretionary powers, while allowing a measure of flexibility to be retained. Those considerations point away from the view that the meaning of the plan is in principle a matter which each planning authority is entitled to determine from time to time as it pleases, within the limits of rationality. On the contrary, these considerations suggest that in principle, in this area of public administration as in others (as discussed, for example, in R (Raissi) v Secretary of State for the Home Department[2008] QB 836 ), policy statements should be interpreted objectively in accordance with the language used, read as always in its proper context. 19. That is not to say that such statements should be construed as if they were statutory or contractual provisions. Although a development plan has a legal status and legal effects, it is not analogous in its nature or purpose to a statute or a contract. As has often been observed, development plans are full of broad statements of policy, many of which may be mutually irreconcilable, so that in a particular case one must give way to another. In addition, many of the provisions of development plans are framed in language whose application to a given set of facts requires the exercise of judgment. Such matters fall within the jurisdiction of planning authorities, and their exercise of their judgment can only be challenged on the ground that it is irrational or perverse (Tesco Stores Ltd v Secretary of State for the Environment[1995] 1 WLR 759 , 780 per Lord Hoffmann). Nevertheless, planning authorities do not live in the world of Humpty Dumpty: they cannot make the development plan mean whatever they would like it to mean.”
“– any adverse impacts of doing so would significantly and demonstrably outweigh the benefits, when assessed against the policies in this Framework taken as a whole; or - specific policies in this Framework indicate that development should be restricted.”