In Watt, R (on the application of) v London Borough of Hackney & Anor  EWHC 1978 (Admin), the High Court quashed the grant of permission for a mixed use development likely to adversely affect sunlight reaching adjacent open land used by the neighbouring school for children’s play. The application had been considered on the basis the redevelopment of the vacant site would have enhanced the character and appearance of the conservation area.
The authority relied on a daylighting report addressing the extent of reduction in daylight to the play land at different times of year. A claim for judicial review was made on several grounds and independent assessment – carried out after the claim – identified flaws in the original report, exaggerating the existing levels of daylight and so understating (by a third) the effect of the new scheme on the play land.
The judge admitted the new report as part of a ground of claim alleging an error of fact. The defendant authority offered its own evidence in response, but – crucially – did not object to its admission.
Errors of fact can be fatal
The judgment confirms that the error of fact justified quashing the permission in the circumstances: there was a factual error which created a misleading picture; the fact was ‘established’, in the sense of being uncontentious; neither the appellant (nor his advisers) were responsible; and finally, the error played a material part in the reasoning (on the basis that it was impossible to say that had not done so, applying Simplex GE (Holdings) Ltd v Secretary of State for the Environment (1989) 57 P&CR 306).
Get your facts right
The daylight reaching the play area was above the relevant policy threshold with the correct analysis (just less far above than the original assessment had, wrongly, suggested). Despite the fact that the error may not have been decisive in the overall decision, though, the judge was prepared to quash the permission. The judgment therefore confirms the risk that faulty technical work creates for planning decisions, even where the error itself is not decisive.