g) Unless there has been some clear error of law in the decision-maker’s
approach, the court should not intervene. This kind of case is a good test of the
principle stated by Lord Carnwath in Hopkins Homes Ltd. v Secretary of State
for Communities and Local Government [2017] 1 W.L.R. 1865 (at paragraph
25) – that “the courts should respect the expertise of the specialist planning
inspectors, and start at least from the presumption that they will have
understood the policy framework correctly” (Catesby Estates Ltd v Steer
[2019] 1 P. & C.R. 5 per Lindblom LJ at [30]).
Impact of the development on the historic environment – the Inspector’s approach
32. In order to understand the Inspector’s approach to the question of harm, it is necessary
to understand how matters were put to him. The main parties disagreed on the correct
approach to the assessment of harm to the significance of heritage assets. The position
of the applicant, the Secretary of State, was that for substantial harm to be
demonstrated “very much if not all of the significance is drained away or that the
asset’s significance is vitiated altogether or very much reduced”. This was said to be
the threshold for substantial harm set down in the case of Bedford Borough Council v
Secretary of State [2012] EWHC 4344 Admin. In contrast, the local planning
authority, Westminster Council relied on the Planning Practice Guidance and the
guidance that ‘substantial’ harm to the significance of a heritage asset can arise where
the adverse impact of a development “seriously affects a key element of (the asset’s)
special architectural or historic interest” (paragraph 18)
33. The Inspector recorded the differences between the parties and his view of matters at
IR15.11 and 15.12:
“15.11 In addition to disagreements on the magnitude of harm
to DHAs between the parties, there is also divergence in the
methodology to be applied to its calibration. The Applicant
relies on the definition of substantial harm (and the calibration
of lesser harms that flow from it) set out in the Bedford case,
broadly defined as a high test. WCC on the other hand (though
not making express reference to it in written evidence) prefer to
rely on the example of substantial harm set out in paragraph
018 of the PPG, a definition, as I understand it from their oral
evidence, which sets the test at a lesser height. Although also
reliant on the PPG definition (but again with no reference in
written evidence) TIS.SVTG & LGT apply a further, different
approach, based on consultancy-developed methodologies for
characterising the magnitude of harm. Lastly, other parties
present a similar Bedford-based approach to harm calibration,
though conclude that the magnitude of harm, specifically with
regard to VTG as an RPG, should be judged as substantial.”
“15.12 My interpretation of this point, also bearing in mind
paragraph 018 of the PPG has been formulated in light of the
Bedford judgement, is that there is in fact little to call between
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