The Mount Cook principles reaffirmed

The Court of Appeal has reaffirmed the Mt Cook principles on materiality of alternative use in the latest stage of the ‘stripey house’ case. Paul Brown QC explains the outcome.

The Court of Appeal has handed down judgment in Lisle-Mainwaring and the Secretary of State for Communities and Local Government v Carroll [2017] EWCA Civ 131. The case is the latest round in the battle over the redevelopment of the No. 19 South End (more widely known as the “stripey house”) in Kensington and Chelsea.

The case concerned a challenge by the owner of the neighbouring property to the grant of planning permission, on appeal, for the change of use of No. 19 from B8 to residential use. When purchased by Mrs Lisle-Mainwaring, the building had last been in active use as an office falling within use class B1, but this had been changed to B8 under permitted development rights. Two previous appeal decisions granting permission for the change of use (and construction of a basement) had been quashed by the High Court, but a third planning inspector had granted permission for the change of use on the grounds that the change from B8 to C3 was in accordance with the development plan. In so doing, he rejected Mr Carroll’s argument that the change from B1 to B8 had been a sham, and that permission should be refused on the grounds that refusal would lead to a resumption of the B1 use.

In the High Court, Lang J quashed this decision on the grounds that the Inspector had failed to grapple properly with Mr Carroll’s argument. The Court of Appeal has now overturned that decision.

Citing the judgment of Auld LJ in R (Mount Cook Land Ltd) v. Westminster City Council, Lindblom LJ said that the law was clear on the circumstances in which a potential alternative future use of the site on which development was proposed was a material consideration. The Mount Cook principles aligned with “the most fundamental principle of development control decision-making:  that an application must be determined on its own merits, in accordance with the statutory scheme”.  If the proposed development was acceptable in its own right, the alternative proposal was normally irrelevant. Alternative proposals would only be material in “exceptional circumstances”, and even then, only if the alternative was not “inchoate or vague” and there was a “real possibility” of its being implemented in the foreseeable future.

Against this backdrop, the “loss” of the benefit of a possible alternative use could not qualify as “planning harm” which would bring the case within the exceptional circumstances test, because this would be inimical to the very requirement that circumstances had to be exceptional.

On the particular facts, the Inspector had concluded that a resumption of the B1 use could not properly be anticipated, and that conclusion was unimpeachable. He had not regarded this as a case in which there were exceptional circumstances, and this was, in truth, a “perfectly unexceptional case”. His decision should not have been quashed.

Paul Brown QC is a barrister at Landmark Chambers and appeared for Mrs Lisle-Mainwaring, the First Appellant. Katrina Yates, also of Landmark, appeared for the Secretary of State, the Second Appellant.