Appeal 6001927

The appeal is dismissed.

The appeal submission includes [name] dated 13 and 21 November 2025. This additional information includes swept path analysis and proposed access arrangement plans, including refuse storage. I have accepted this additional technical information for consideration, as this does not materially change the appeal proposal, and would thus not prejudice interested parties.

Although not forming a refusal reason, the Council’s appeal statement sets out that the claimed exemption from mandatory [name] (BNG) would require a completed s106 legal agreement or unilateral undertaking, to legally secure the proposed dwellings as self-build and custom development. This is disputed by the appellants, who consider that this can be secured using planning conditions. Whilst not cited in the refusal reason given, the Council’s evidence indicates conflict with London Plan Policies D3 and D6 in terms of providing safe, inclusive, and legible access to the proposed dwellings. This is also disputed by the appellants.

In light of all the above, the main issues are:  whether the proposed development is exempt from BNG and if not exempt, whether the proposal would secure BNG;  the effect of the proposal on the Chislehurst Conservation Area; and  whether future occupiers of proposed dwellings would be provided with suitable access provision.

On 02 April 2024, the Environment Act 2021 statutory provisions relating to BNG came into force for smaller sites such as the appeal site. This is principally set out under Schedule 7A ([name] in England) of the Town and Country Planning Act 1990 ([name]). Under this statutory framework, subject to some exceptions, every grant of planning permission is deemed to have been granted subject to the condition that the biodiversity gain objective is met. This objective is for development to deliver at least a 10% increase in biodiversity value relative to the pre-development biodiversity value of the onsite habitat.

Article 7(1A) of the Town and Country Planning (Development Management Procedure) Order 2015 ([name]) (the 2015 Act) requires applications for planning permission to be accompanied by certain information relating to BNG, except where one of the exemptions specified in the legislation applies. The information required includes a declaration as to whether the applicants believe that the BNG provisions apply to the application, and if not, the reasons why.

The appellants have indicated on the application form that the appeal scheme would be a type of self-build and custom development that is exempt from BNG. Self-build and custom build is also included in the description of development provided in the application form.

Additionally, the appellants have provided a self/custom build proforma that sets out how the scheme would meet the definition of “self-build and custom housebuilding” as set out in sections 1(A1) and (A2) of the 2015 Act. This definition establishes that the new dwellings must be occupied by the person or persons responsible for carrying out or commissioning the building.

The proforma indicates that the appellants have designed and intend to build the proposed dwellings for themselves to occupy. [name] accept that the appellants’ intention is to build and occupy the proposed dwellings, this is not enough, on its own, to qualify as self-build or custom dwellings. Due completion of the proforma does not in itself bind the appeal scheme as self-build and custom housebuilding, or conversely, the BNG regulations and the conditions of its exemptions.

Without prejudice, the Council has provided a suggested condition to secure the scheme as a self-build, in the event that I allow the appeal. A self-build condition would however fail to satisfy the tests in paragraph 57 of the Framework. This is because the absence of an appropriate legal mechanism before me, such as a S106 agreement or unilateral undertaking, means that the BNG exemption is not secured with a sufficient degree of legal certainty, namely in terms of enforceability.

In light of all the above, in the specific circumstances of this case, I am not satisfied that it has been demonstrated that the appeal scheme before me could be secured as a self-build and custom development. It thus does not qualify for the legislative exemption from BNG in this respect, and the submitted evidence before me does not demonstrate that any of the other BNG legislative exemptions would apply.

Where none of these BNG exemptions apply, the applicant is required to provide a completed biodiversity metric calculation demonstrating the on-site habitat value, as well as a number of other related details as listed in sub-paragraph (c) of the aforementioned Article. Such information is however not before me. Adequate provision of BNG has therefore not been demonstrated.

In conclusion, for the above reasons the proposal fails to demonstrate adequate BNG legislative exemption or provision. It would therefore conflict with the statutory provisions relating to BNG, as already set out above. In this respect, the proposal also conflicts with Policy G6 of the London Plan which requires development proposals to aim to secure net biodiversity gain. It would also conflict with paragraph 187(d) of the Framework which requires planning decisions to provide net gains for biodiversity.

The appeal site lies within Sub-Unit 5 ( [site address] ) of the CCA. Section 72 of the Planning (Listed Buildings and Conservation Areas) Act 1990 (the Act) requires special attention be paid to the desirability of preserving or enhancing the character or appearance of a Conservation Area. From what I have seen and read, the CCA’s significance is derived from its diversity of historical development forms and uses, and its extensive open space, private garden areas and mature tree coverage.

The submitted evidence before me indicates that the proposal site has been physically and functionally separated from the [address] apartments for a number of years. Low-level scrub encompassed its grounds at the time of my site visit, and it also contains a number of trees which are visible from beyond the site. Its fenced enclosure and somewhat overgrown condition mean that it does not have the visual appearance or functionality of garden land.

Nonetheless, the appeal site makes a positive contribution to the significance of the CCA as a heritage asset, even though it is not entirely visible from surrounding vantage points. This contribution is derived from the site’s undeveloped and verdant appearance, in a location mainly surrounded by spacious residential gardens containing tall trees.

The design of the proposed dwellings takes inspiration from [name], a Victorian pair of semi-detached dwellings on nearby [address]. However, the proposed dwellings would be sited at some distance from surrounding residences and whilst there are some other backland buildings in the immediate vicinity, they are single storey and appear ancillary to the dwellings they serve.

The scheme would require removal of 19 trees appreciable from surrounding vantage points, despite presence of larger trees surrounding much of the site. I accept the low-quality categorisation in the Tree Survey and Arboricultural Impact Assessment report, and that the Council’s Tree Officer raised no objection. However, the proximity of the proposed dwellings to the front and side boundaries, and the requisite parking and turning space within the site, limits the extent of new tree planting possibilities. I therefore do not envisage that the quantitative extent of tree loss would be fully mitigated by new planting in visual or landscape terms.

Although views of the proposed dwellings from [site address] would be limited to filtered glimpses, the built form would be significantly more visible from surrounding residential properties and their private gardens. Other crown roof examples are at some distance away from the proposal site and are outliers that do not appear to constitute historic fabric. In this context, the proposed crown roof form would be conspicuous and visually harmful, and the dwellings would appear cramped and squeezed in amongst the more spacious surrounding plots, despite spacing of more than 1m from the side boundaries as sought by LP Policy 8.

Change within a conservation area does not automatically equate to heritage harm or an in-principle objection. However, for the above reasons, I conclude that the proposal would conflict with Policies 4, 37 and 41 of the Council’s Local Plan (LP) (adopted 2019), and London Plan Policies D3, DC3 and HC1. These policies require, amongst other things, development to preserve and respect heritage assets that contribute towards local character and conserve their significance, to complement layout, scale and form of existing buildings and spaces, and to incorporate existing landscape features that contribute to the area’s historic value.

Paragraph 212 of the Framework sets out that when considering the impact of development on the significance of a DHA, great weight should be given to its conservation. Framework paragraph 213 sets out that any harm to the significance of a DHA should require clear and convincing justification. I have found the harm to the CCA to be less than substantial, but of considerable importance and weight. Under such circumstances, Framework paragraph 215 states that this harm should be weighed against the public benefits of the proposal.

No public benefits relating to heritage matters are before me. However, the Council’s latest published five-year housing land supply covering the period 2024/25 to 2028/29 is 1.93 years, which it acknowledges as a very significant undersupply. The latest [name] (HDT) results published by the Government in December 2024 shows the Council's HDT result as 58% (i.e. between the financial years of 2020-2023, there were only 58% as many completions as the number of homes required).

The above evidence indicates that there has been a substantial and persistent shortfall in housing delivery across the Council in recent years. Provision of two family-sized dwellings would form a minor but positive contribution to the Council’s housing supply. The public benefits arising from this are afforded significant weight when having regard to the extent and duration of the Council's housing supply shortfall. Such public benefits are of sufficient weight to outweigh the less than substantial harm to the significance of the CCA and in turn, the conflict with the abovementioned development plan policies.

As such, there would be no conflict with the Framework’s historic environment protection policies. In the context of Framework paragraph 11d)i and its footnotes 7 and 8, the impact on the CCA does not provide a strong reason for refusing the development proposed. It thus follows that there would be no conflict with Policy 3 of the LP insofar as the character and appearance impacts, and the loss of landscaping in a backland site context, would not be unacceptable.

Refuse bins serving the proposed dwellings would be stored on a temporary basis on collection days only adjacent to the existing refuse storage facility serving [address]. Even if this could become a more permanent situation on account of the distance in which future occupiers would have to travel with their refuse, views along [site address] would be sufficiently screened by the front brick and rail enclosure and nearby shrubbery to avoid an adverse visual impact. There would thus be no conflict with LP Policy 37 in this respect.

The access route along and behind [address] to the proposed dwellings is relatively long. However, the swept path plans before me adequately demonstrate that this route would not compromise the parking spaces serving [address].

The proposed refuse collection point near to the [site address] vehicular entrance would also not obstruct the access route. The route width and its relationship to the existing [address] layout is not demonstrably unsafe for pedestrian or cycle use. Permeability would therefore not be compromised. In turn, future occupiers of the proposed dwellings would not be isolated.

Given the fire appliance hose carry distances from [site address] to the proposed dwellings, a sprinkler system to be installed in accordance with [name] is suggested. [name] been minded to allow the appeal, details of this system could have been secured by means of a suitably worded planning condition, to ensure sufficient fire safety. The proposal would provide active frontages and the access route for future occupiers would be well-overlooked by [address]. I therefore do not envisage any adverse security implications. I have thus found no conflict with the London Plan Guidance Housing Design Standards in these respects.

I therefore conclude that future occupiers of proposed dwellings would be provided with suitable access provision. The scheme would thus comply with London Plan Policies D3 and D6 in this respect which require, amongst other things, clear, convenient and legible routes to buildings to provide safe and secure environments.

I am directed to the Minister of State for Housing and Planning’s announcement on 17 December 2025 that it is the Government’s intention to remove smaller developments of up to 0.2 hectares from the BNG requirement. This has however not been enacted at the time of this decision. Moreover, there is no guarantee that such an exemption would apply to the appeal scheme, as it could conceivably be subject to a transitional period excluding proposals already submitted and/or determined. This matter therefore does not justify allowing this appeal.

The reason for refusal cites conflict with Policy D4 of the London Plan. This policy refers to, amongst other things, masterplans and design codes based on the requirement set out in [name] of London Plan Policy D3. This part of Policy D3 however refers to “higher density developments”. Policy D4 is therefore not relevant to the appeal scheme comprising two dwellings within a settlement area.

Conflict with the Council’s Urban Design Guide Supplementary Planning Document (SPD) (adopted 2023) is also cited. The SPD is detailed and wide-ranging and whilst certain extracts are cited in the Council’s evidence, it has not set out where the specific conflict with this guidance lies. Conflict with this SPD has therefore not been demonstrated.

The proposal would comply with LP Policy 32 in terms of avoiding a significantly adversely effect on road safety. It would also comply with the Government’s nationally described space standard, and London Plan Policy D6 F in respect of private outside space provision. An absence of material conflict with national and local policies, supporting guidance, or technical objection from specialist consultees, however neither weighs in favour nor against allowing this appeal.

The appellants prepared the application with the input of a detailed technical consultant team, and have perceived the consultation responses from the Council’s Conservation Officer and [name] to be somewhat contradictory. The Council also did not request a legal agreement to secure self-build at validation stage or prior to its decision.

I can understand how the above process could have been frustrating for the appellants. I am however dutybound to make my own assessment of the proposal based on the relevant legislation, policy, site-specific circumstances and evidence before me. Assessing design matters and heritage asset impact inevitably includes a degree of subjective assessment.

I have found fundamental conflict with Policy G6 of the London Plan which requires development proposals to aim to secure net biodiversity gain. This amounts to conflict with the development plan taken as a whole. Given the statutory requirement to secure BNG for new development such as that proposed, I afford this conflict substantial weight.

I have also found that the effect on the CCA as a designated heritage asset does not provide a strong reason for refusing the development proposed. There is nothing before me to indicate that the other policies in the Framework’s footnote 7 are relevant in this case. Presently, there is a very significant housing undersupply amounting to 1.93-years, and it appears that a shortfall in this Borough has persisted for several years.

Hence, the balance in Framework Paragraph 11d)ii is applicable. This states that permission should be granted unless any adverse impacts would significantly and demonstrably outweigh the benefits, when assessed against the policies in the Framework taken as a whole, having particular regard to specified key policies.

Of particular relevance to the issues in which this decision turns on, the scheme would make an efficient use of land within a sustainable location, within walking distance to [site address] and [address], and a number of bus stops providing regular services to wider destinations. The proposal derives support from Framework Paragraphs 110, 115 and 129 in these respects.

Provision of two family-sized dwellings would provide a minor but positive contribution to housing supply. Small sites make an important contribution to meeting the housing requirement of an area and can be built out relatively quickly. The public benefits arising from this are thus afforded significant weight.

However, in the absence of evidence to the contrary, allowing this appeal would lead to fundamental conflict with London Plan Policy G6, the statutory provisions relating to BNG, and Framework paragraph 187(d) which requires planning decisions to provide net gains for biodiversity. Taking all matters into consideration, I conclude that the adverse impacts that would arise from this would significantly and demonstrably outweigh the benefits. Material considerations in this case do not indicate that the proposal should be determined other than in accordance with the

For the reasons given above, the appeal is dismissed.