AC-2024-LDS-000251 - [2025] EWHC 2256 (Admin)

There was some discussion about the scope of the permission granted by the learned deputy judge in respect of the fourth ground. She was not convinced that the BNG figures presented to the committee were inaccurate. Nonetheless she granted permission to proceed on the fourth ground, without any limit. It follows that the permission is to make the case pleaded in the statement of facts and grounds (SFG), which is at paragraphs 88 to 100 of the SFG.

The gist of the case in those paragraphs is as follows. The officer’s report (at 10.66) stated that the Heybeck Lane site BNG calculation by the developer using the Biodiversity Metric 3.1 “confirms the proposed development would achieve the following net gains (post-intervention)”: 10.03 per cent for habitat units and 10.61 per cent for hedgerow units. However, officers conceded orally that an updated BNG assessment would be needed.

Despite that concession, BNG was not the subject of a condition. It was addressed in Schedule 5 to the section 106 agreement which would proceed from “the pre-development biodiversity value of the site”. However, the “pre-development” value could be affected adversely by “enabling works” which could degrade the biodiversity value and thus cause it to proceed from a lower baseline than the baseline at the time the BNG figures in the officer’s report were notified to the committee in December 2022.

The claimant’s concern is that the committee was not told that the developer could degrade the biodiversity value of the site by enabling works and then measure the required 10 per cent gain in a post-enabling works Biodiversity Assessment measuring the gain from a lower baseline. The claimant says the committee was thereby misled or erred in law by taking into account as a material consideration the prospect of achieving the stated BNG.

It is no answer, the claimant pleads at SFG paragraph 88, for the LPA to point to paragraph 5(a) of Schedule 7A to the 1990 Act, requiring pre-development biodiversity to be measured as at the date of the planning application and not later. While members may be expected to have some knowledge of planning law and practice, the existence of that provision cannot by itself entail that the committee members were confident the baseline would not be lowered in the updated biodiversity assessment or were aware of the issue.

In Ms Byrd’s skeleton argument, she repeated the simple point that members were not told the developer could do significant works before the updated Biodiversity Assessment was carried out. The claimant does however accept that the definition of the “pre-development biodiversity value of the site” is now clearer in the new clause 3.3 introduced in SPO (2).

But, Ms Byrd submits, the developer could arguably still carry out “ground works” before complying with the covenants at clauses 3.1.1 to 3.3.3, i.e. before the updated Biodiversity Assessment. Ground works are not clearly included in “any works associated with the Development” in replacement clause 3.1. “[G]round works” are referred to in condition 6 and may not be done before approval of the CEMP. They are excluded from the definition of “[s]ite preparation” in condition 1. That excluded works are:

“excavation, remediation, grading and other activities related to the modification of the ground surface or subsurface”.

The claimant then says that even if the timing issue is resolved by SPO (1) and (2), three points remain under the fourth ground. First, ground cover on the site that is not a “feature of potential ecological importance” can be cleared; for instance, grassland and field margins. Second, further ecological surveys may impact on the achievement of the BNG of 10 per cent. The prediction of a 10 per cent BNG was not accurate. Third, the committee was told that the BNG would be achieved on-site or primarily on-site; while the section 106 agreement did not distinguish between on- and off-site interventions.

The LPA and developer say the second and third points are unpleaded and not open to the claimant and in any event devoid of merit. As to the first point, Mr Carter points out that Schedule 5 to the section 106 agreement defines the “Biodiversity Assessment” as one including Biodiversity Metric calculations and which sets out “details of the pre-development biodiversity value of the site”; and that “Biodiversity Metric” is in turn defined as: “the DEFRA biodiversity metric as applicable at the time of the Biodiversity Assessment”.

Thus, says the LPA, the assessment must comply with the latest DEFRA metric, which itself must comply with the requirements for BNG in Schedule 7A to the 1990 Act. Paragraph 5(1) of Schedule 7A defines the pre-development biodiversity value of the onsite habitat as its biodiversity value as at the “relevant date”; which, (by paragraph 5(2)(a)) is the date of the planning application, here in July 2020. Thus, the baseline for BNG must be true to the latest DEFRA metric, which must require it to be calculated as at July 2020.

Further, Mr Carter submits, any relevant “ground works” would be caught by clause 3.1.3 of SPO (1), providing for the biodiversity assessment to be carried out, submitted and approved by the LPA before commencement of development and before clearance of any hedgerows, trees and shrubs or any other features of potential ecological importance within the site. Any ground works that did not affect a feature of potential ecological importance would have no ecological impact and can therefore be disregarded.

Furthermore, SPO (2) puts the matter further beyond any doubt because it provides in terms that the pre-development biodiversity value of the site refers to the ecological site at the earliest of three points in time, all of which must necessarily have fallen before the carrying out of any works that could affect the ecological value of the site. There is thus no prospect of the BNG baseline being artificially lowered.

The developer’s submissions were to similar effect. In the original section 106 agreement, said Mr Booth KC, the pre-development biodiversity value (“development” not being capitalised and not caught by definitions including that word) can only mean “the value as assessed prior to any works connected with the scheme whatsoever, be they clearance works such as the ‘enabling works’, or any other works.” The baseline must therefore be “the …. state of the site, prior to any works connected with the scheme.”

The developer’s submissions then mainly echoed those of the LPA. The fourth ground was answered by SPO (1) and the deputy judge was wrong to grant permission in respect of it. Alternatively, the matter was put beyond any doubt by SPO (2) and the fourth ground should be dismissed. The point about “ground works” was without merit. The additional matters relied on went beyond the pleaded case and did not benefit from permission. The accuracy of the BNG forecasts in the officer’s report was a matter of planning judgment which could not be impugned save on Wednesbury grounds.