Heritage Harm and the Balancing Exercise: What the Case Law Actually Says

Heritage is the area of planning most likely to end up in court. The reason is straightforward: the policy framework requires a balancing exercise between harm to heritage significance and public benefits, and that balance involves judgement. Where there is judgement, there is scope for challenge.

But the legal framework is now well established through a series of important court decisions. Understanding what the case law actually says (rather than what people assume it says) is essential for anyone proposing development that affects heritage assets.

The August 2026 NPPF sets out a clear hierarchy for heritage decision-making. Policy HE6(1) states that when considering the potential effect of a development proposal on the significance of a designated heritage asset, substantial weight should be given to the asset's conservation (and the more important the asset, the greater the weight should be), irrespective of whether any potential effect amounts to a positive effect, harm, substantial harm, or total loss of its significance.

This "substantial weight" requirement (earlier editions said "great weight") is not discretionary: it applies in every case where a designated heritage asset is affected. It applies to Grade II listed buildings just as it applies to Grade I. It applies to conservation areas. It applies to the setting of heritage assets as well as their physical fabric.

Policy HE6(5) deals with substantial harm or total loss. Where a proposal would cause substantial harm to, or the total loss of, the significance of a designated heritage asset, consent should be refused unless the harm is necessary to achieve substantial public benefits that outweigh the harm or loss, or unless all four conditions in HE6(5)(a) to (d) apply, which together require that the nature of the asset would otherwise prevent all reasonable uses of the site, that no suitable use can be found in the medium term through appropriate marketing, that conservation by grant-funding or not for profit, charitable or public ownership is not possible, and that the harm or loss is outweighed by the benefit of bringing the asset back into use. Policy HE6(6) adds that such harm to grade II listed buildings or grade II registered parks or gardens should be exceptional, and to assets of the highest significance wholly exceptional.

Policy HE6(4) deals with harm, the test that applies in the vast majority of heritage cases. Where a proposal would harm the significance of a designated heritage asset, the effect on the asset and its significance should be weighed against any public benefits resulting from the proposal. This is the "balancing exercise" that dominates heritage planning. The August 2026 Framework no longer uses the December 2024 category of "less than substantial harm". Policy HE5(2) asks instead whether a proposal would have a positive effect, no effect, harm (with the degree of harm identified), or cause total loss, and policy HE5(2)(c) states that substantial harm "would occur where the development proposal would seriously affect a key element of the asset's significance".

The most important heritage case in planning law is Barnwell Manor Wind Energy Ltd v East Northamptonshire District Council [2014] EWCA Civ 137. The Court of Appeal established that the statutory duty under Section 66(1) of the Planning (Listed Buildings and Conservation Areas) Act 1990, to have "special regard" to the desirability of preserving listed buildings and their settings, requires decision-makers to give considerable importance and weight to any harm to a listed building or its setting.

This goes further than simply noting the harm. The Barnwell Manor principle means that when a decision-maker finds harm to the significance of a listed building, they must treat that harm as having considerable weight in the planning balance. A finding that harm falls below the threshold of substantial harm ("less than substantial harm" in earlier national policy) does not mean the harm is unimportant. It still carries considerable weight by virtue of the statutory duty. Policy HE6(3) of the August 2026 NPPF uses the same formulation: any harm to a designated heritage asset "will be a matter of considerable importance and weight".

The practical consequence is significant. Decision-makers who identify heritage harm and then dismiss it as minor, or who fail to give it the weight required by Section 66(1), are vulnerable to legal challenge. Many planning committee decisions have been quashed on this basis.

Bedford Borough Council v Secretary of State for Communities and Local Government [2013] EWHC 2847 (Admin) was decided by Jay J in July 2013, before the Court of Appeal ruled in Barnwell Manor. The council challenged an inspector's decision to grant permission on appeal, and the challenge failed. The case is known for what substantial harm means: harm through which very much, if not all, of the significance of the asset would be drained away.

That threshold is high, and much heritage harm falls short of it. Harm below it still has to be identified and given considerable importance and weight under the Barnwell Manor principle, and policy HE6(4) of the August 2026 NPPF weighs any harm to a designated heritage asset against the public benefits of the proposal.

Harm short of substantial is not a single category. It is a spectrum, and policy HE5(2)(c) requires the degree of harm to be identified. At one end, harm may be negligible; at the other, it may be just below the threshold of substantial harm. The position on the spectrum affects the weight to be given to the harm and, consequently, the level of public benefits needed to outweigh it.

Under the December 2024 and earlier Frameworks, inspectors and officers routinely placed harm on this spectrum using language such as "at the lower end of less than substantial harm," "moderate less than substantial harm," or "at the upper end of less than substantial harm." Our analysis of appeal decisions shows that the position on the spectrum is often the decisive factor: schemes causing harm at the lower end are far more likely to be approved in the planning balance than those at the upper end.

Proximity and intervisibility. Development that is directly visible from or adjacent to a heritage asset is more likely to cause harm at the upper end. Development that is screened by existing buildings, topography, or mature vegetation causes less harm.

Contribution to significance. The setting of a heritage asset contributes to its significance to varying degrees. A rural farmhouse whose significance derives partly from its agricultural setting will be more harmed by suburban development than one whose significance is primarily architectural.

Quality of design. Inspectors consistently note where proposed development is of high design quality and responds sensitively to heritage context. Good design does not eliminate harm, but it can reduce it on the spectrum.

Reversibility. Harm that is reversible (for example, a temporary structure or a use that can be discontinued) carries less weight than permanent and irreversible harm.

Under policy HE6(4), harm to a designated heritage asset must be weighed against any public benefits resulting from the proposal. The policy itself says important public benefits can include securing the long-term reuse of a vacant or underused listed building, and enabling energy efficiency and low carbon heating measures to be employed. Public benefits are broadly defined and can also include:

Housing delivery: particularly affordable housing, which inspectors consistently identify as a significant public benefit. Policy HO7(1) of the August 2026 NPPF directs that, in applying the policies in the Framework, substantial weight should be given to the benefits of providing homes which will contribute towards meeting the evidenced accommodation needs of the community.

Economic benefits: job creation, local spending, business rates, and economic regeneration. These are material but typically carry less weight than housing delivery unless the economic case is exceptional.

Heritage benefits: enabling development that funds the repair or restoration of a heritage asset at risk. This is given significant weight where the asset is on the Heritage at Risk Register or in demonstrable need of investment.

Community benefits: public open space, community facilities, improved access, and other benefits that serve the wider community.

The critical point is that the benefits must be public benefits, not private ones. A developer's profit is not a public benefit. Increased land value is not a public benefit. The benefits must accrue to the community or the public interest.

The heritage framework is demanding but navigable. Our analysis of successful schemes in heritage-sensitive locations identifies several practical principles:

Commission a Heritage Statement early. The heritage assessment should inform the design, not be retrofitted to justify it. Schemes designed with heritage in mind from the outset are far more likely to succeed.

Be honest about harm. Applicants who claim "no harm" when harm clearly exists lose credibility with officers and inspectors. It is far better to identify the harm honestly, place it on the spectrum, and then demonstrate that the public benefits outweigh it.

Articulate public benefits clearly. The balancing exercise requires benefits on the other side of the scale. If you do not articulate them, the officer has nothing to weigh against the harm.

Engage with the conservation officer. Conservation officers provide specialist advice to case officers on heritage matters. Early engagement can identify concerns before they become reasons for refusal.

Heritage planning is not a barrier to development. It is a framework for ensuring that development respects the historic environment. Understanding the case law, applying the correct framework, and presenting honest evidence gives applicants the best chance of navigating it successfully.