- Decision
- dismissed, 1 October 2026
- Decided by
- Planning Inspector: N Teasdale
- Authority
- Harrow (London)
- Appeal reference
- 6006890
- Application reference
- PL/2018/25
- Procedure
- written representations
- Development
- Outline permission (access reserved) for demolition of a rear garage and erection of a two-storey house in the rear garden
- Homes
- 1
- Site context
- inside settlement, garden land
- Green Belt
- No
- Framework applied
- August 2026 NPPF
- Determinative policies
- BNG (Sch 7A TCPA), N2, S4(1)
- Development plan policies
- London Plan 2021 G6, H2, London Borough of Harrow Local Plan 2021-2041 (2026) GR10, GI3, HO3, Garden Land Development SPD 2013
- Main issues
- biodiversity net gain; garden land development
Summary
An outline scheme for a two-storey house in a rear garden in Harrow was dismissed on biodiversity net gain (BNG) alone. The inspector held that the newly adopted Local Plan's requirement for "comprehensive" garden-land development was materially inconsistent with L2 and gave it very limited weight, so the location was acceptable. But the de minimis exemption was not shown, no baseline was provided, and that failure substantially outweighed the benefits under S4.
Issues and findings
- Transition. "There have been significant amendments made against the 2024 version, and the parties have had the opportunity to comment on the changes in relation to this appeal" (DL ¶5).
- BNG: FAIL. "the de minimis exemption applies strictly to the total area of habitat impacted by the development. It does not look at the net outcome or how much habitat is intended to be restored" (DL ¶12). "I am not sufficiently satisfied that the biodiversity gain condition is capable of being successfully discharged" (DL ¶15).
- Local policy GR10(b): CONFLICT. "The small-scale nature of the proposals and its site size cannot reasonably be considered as making a comprehensive use of land" (DL ¶27).
- L2(1)(d): PASS. "The proposed development can however be reasonably considered as being broadly capable of meeting Policy L2 criteria" (DL ¶37).
- Plan weight, Annex A ¶2. "Parts of the criteria are different to those set out in Policy GR10 of the LP and can be reasonably described as less restrictive" (DL ¶38). "This part of the policy is therefore materially inconsistent with the Framework’s national decision-making policies" (DL ¶38). "very limited weight should be attached to criteria (b) of Policy GR10 and the associated SPD relating to garden land development" (DL ¶39).
Planning balance
S4(1). Substantial weight to an additional home within a residential curtilage (DL ¶42). Against: "This failure constitutes a severe environmental harm which is of such overriding importance that it substantially outweighs the benefits of the scheme when assessed against the national decision-making policies in the Framework" (DL ¶43). The inspector also said that without the statutory minimum "I do not have the legal authority to grant permission" (DL ¶43). The conclusion is plan-led (DL ¶45).
What made the difference
The absence of a habitat baseline and metric. On the same site, the same inspector allowed two bungalows the day before (PINS-6004526), where the baseline was established and the gain condition was found capable of discharge. Here the appellant's own arithmetic put the affected habitat above 25 sq m.
Transferable points
- A local garden-land policy that adds a "comprehensive use of land" requirement is more restrictive than L2(1)(d) and gets very limited weight under Annex A ¶2, even in a plan adopted in 2026 (DL ¶6, ¶38–39). The letter does not discuss the Annex A ¶2 exception for plans examined and adopted against the new Framework.
- An SPD that interprets the inconsistent policy loses weight with it (DL ¶39).
- The BNG de minimis threshold is measured on habitat affected, not net of restoration (DL ¶12).
- A decision-maker must be satisfied the statutory gain condition can be discharged; without the Article 7 baseline information it cannot be (DL ¶14–15).
- Failure to show BNG can decide an S4 balance on its own against a substantial-weight L2 benefit (DL ¶42–43).
Policy findings
Policy codes are those of the National Planning Policy Framework (August 2026) unless a development plan is named.
| Policy | Finding | Weight | Note |
|---|---|---|---|
| BNG (Sch 7A TCPA) | fail | de minimis exemption not shown; even on the appellant's figures 29.45 sq m of habitat is affected, above the 25 sq m threshold; no baseline or metric, so the biodiversity gain condition is not shown capable of discharge (DL 10-17) | |
| N2 | conflict | contrary to N2 "relating to improving the natural environment"; no limb given (DL 17); called "a severe environmental harm" in the balance (DL 43) | |
| L2(1)(d)(iii) | pass | substantial | additional unit within a residential curtilage; footprint and 50% retention criteria met; other L2 criteria not disputed or for reserved matters (DL 37, 40, 42) |
| Transitional(2) | conflict | very-limited | criterion (b) of LP GR10 (garden land only where it makes a comprehensive use of land) and the Garden Land SPD are more restrictive than L2, so materially inconsistent; plan adopted during the appeal (DL 6, 38-40) |
| S4(1) | fail | location acceptable in principle, but the BNG failure substantially outweighs the benefits (DL 41-43) |
Key facts
- Harrow Local Plan 2021-2041 was adopted during the appeal and superseded the policies cited in the refusal (DL 6)
- Appellant's own figures give 3.85 m x 7.65 m = 29.45 sq m of affected habitat (DL 11-12)
- The de minimis exemption looks at the total area of habitat affected, not the net outcome after restoration (DL 12)
- Council had granted two bungalows on the adjoining strip (PL/0427/26) where a BNG baseline was provided (DL 16)
- Two other appeals on the same site, 6005188 and 6004526, decided by the same inspector (DL 4)
- A 2023 appeal for a dwelling at the rear of the site was dismissed (APP/M5450/W/22/3307386) (DL 30)
- Costs application by the appellant against the Council, the subject of a separate decision (DL 2)
- Parties had the opportunity to comment on the August 2026 Framework (DL 5)
Related decisions
Sources
This note is one of the decisions behind the NPPF 2026 Navigator, which shows how each Framework test has been applied across all the decisions in the database. Also available as Markdown.