31. The legal framework for consideration of the impact of a proposed development on relevant heritage assets was common ground: a) In considering whether to grant planning permission the decision maker is under a general duty to pay special regard to the desirability of preserving the listed buildings potentially affected by the proposals, their settings and any features of special architectural or historic interest which they may possess (Section 66(1) of the Planning (Listed Buildings and Conservation Areas) Act 1990). In this case, the Listed buildings include the Buxton Memorial (Grade II* listed building). b) The significance of a heritage asset derives not only from an asset’s physical presence, but also from its setting. Great weight should be given to the asset’s conservation. The more important the asset, the greater the weight that should be given to conservation. Harm to the significance of a designated heritage asset requires clear and convincing justification (NPPF 199, 200). c) Where potential harm to designated heritage assets is identified, it needs to be categorised as either ‘less than substantial’ harm or ‘substantial’ harm (which includes total loss) in order to identify which policies in the NPPF apply (NPPF 200-202). Accordingly, the key concept is whether the harm will be ‘substantial’. d) Substantial harm to grade II listed buildings or registered gardens (which would include Victoria Tower Gardens) should be exceptional. Substantial harm to assets of the highest significance, notably grade II* listed buildings (which will include the Buxton Memorial) should be wholly exceptional. For development that will lead to substantial harm to a designated heritage asset, consent should be refused unless it can be demonstrated that the substantial harm is necessary to achieve substantial public benefits that outweigh that harm (NPPF paras 200- 201). e) Where a development proposal will lead to less than substantial harm to the significance of a designated heritage asset, this harm should be weighed against the public benefits of the proposal (NPPF 202). f) Whether a proposal causes ‘substantial harm’ or ‘less than substantial harm’ will be a matter of judgment for the decision-maker, having regard to the circumstances of the case and the policy in the National Planning Policy Framework. In particular; the effect of a particular development on the setting of a listed building – where, when and how that effect is likely to be perceived, whether or not it will preserve the setting of the listed building, whether, under government policy in the NPPF, it will harm the “significance” of the listed building as a heritage asset, and how it bears on the planning balance – are all matters for the planning decision-maker. This is subject to the decision maker giving considerable importance and weight to the desirability of preserving the setting of a heritage asset (Catesby Estates Ltd v Steer [2019] 1 P. & C.R. 5 per Lindblom LJ at [30]). 10