Biodiversity net gain and planning permission

A refusal of planning permission for a quarry has been quashed over an error on biodiversity net gain. Jenny Wigley KC looks at the lessons from the case.

In a High Court judgment in NRS Saredon Aggregates Ltd v Secretary of State for Levelling Up, Housing and Communities & Anor [2023] EWHC 2795, Mr Justice Eyre has quashed an Inspector’s decision refusing planning permission for a sand and gravel quarry in the Green Belt on the basis of a legal error underlying the weight that the Inspector accorded to biodiversity net gain (BNG).

It was agreed at the inquiry that the scheme would deliver over 39% BNG. The Inspector afforded ‘only moderate weight’ to this on the basis that “some of the biodiversity net gain that would be achieved is required to meet national policy and future legislative requirements in order to mitigate the environmental impact of the development”.

The High Court agreed with the Claimant that the Inspector’s judgement as to weight was affected by a mistaken view as to requirements of forthcoming legislation. Because there was no basis for considering that the legislation might be retrospective, it was plainly not applicable to the scheme to be determined:

“The effect of that interpretation is that when assessing the weight to be attributed to the biodiversity net gain for the purposes of assessing whether there were very special circumstances outweighing the harm to the openness of the Green Belt the Inspector reduced the weight on the basis of a mistaken view as to the law. He did so believing incorrectly that some of the net gain would be required in any event by reason of the forthcoming legislation. That was an error of law and meant that the Inspector exercised his planning judgement as to the weight to be given to that material consideration (namely the net gain) on a basis that was wrong in law.”

The case is a useful way of reminding decision makers that there is, as yet, no legal requirement for 10% biodiversity net gain. The relevant provisions in the Environment Act 2021 have yet to come into force and, when they do (in January, we’re now told), the requirement will only apply to new applications submitted on or after that date. There is a policy requirement in the NPPF for biodiversity net gain, but only that such gain should be positive, i.e above zero, and there are also varying policy requirements in some Local Plans, but still no legal requirement. In emphasising benefits of development proposals, it is useful to stress the degree of BNG being offered and, for all applications already in the system, it is worth pointing out that any degree of BNG goes above and beyond legal requirements and should be afforded due weight accordingly.

Jenny Wigley KC is a barrister at Landmark Chambers. She represented the Claimant.