A Supreme Court ruling on planning permissions underlines the importance for developers of being clear about their plans from the outset

The Supreme Court’s decision late last year on Hillside Parks Ltd vs Snowdonia National Park Authority [2022] UKSC 30 could have wide-ranging implications for developers on how to approach scheme amendments. The case itself is a curious one. Full planning permission for the site had originally been granted in 1967, for 401 homes on land that was not, at that time, part of the Snowdonia National Park. However, by the time the site was acquired by Hillside Parks Ltd in 2017, this had changed, with the site then within the park’s boundaries.

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Over time, numerous planning applications were made, resulting in changes to the scheme which departed from the masterplan submitted as part of the 1967 permission. The planning authority had written to Hillside advising that it was considered impossible to undertake further works under the original permission, and that the developer should immediately stop work on site so that the planning position could be regularised.

Hillside challenged the stance of the planning authority through the courts, seeking confirmation that reliance could continue to be placed on the 1967 permission. However, the court ruled that the subsequent variations had resulted in a scheme which was physically incompatible with the original masterplan, rendering any further development under the 1967 planning permission unlawful. The developer unsuccessfully appealed against this decision in both the Court of Appeal and the Supreme Court, and the ruling sets out key points that could create a significant ripple effect for developers.

Variations had resulted in a scheme physically incompatible with the original masterplan, rendering any further development under the planning permission unlawful

The case reaffirmed the “Pilkington principle”, confirming that overlapping planning permissions cannot coexist where they are incompatible. However, a distinction was then drawn between two broad categories of amendments to planning permissions: those changes that result in a “mere inconsistency” with the original scheme, and those that are “material” and result in physical incompatibility with the original permission. Where a later permission makes it physically impossible to implement or continue with development under an earlier permission, the earlier permission can no longer be relied upon for further development.

This raises questions about what would count as a “material change” as opposed to a “mere inconsistency” and will no doubt lead to future litigation on the point. It also demonstrates that maintaining an open and continuous dialogue with planning officers when seeking to make amendments to any scheme is key, as ultimately the line between “material change” and “mere inconsistency” is a matter of planning judgment.

Another point of note relates to those changes which are “material”. The court held that such variations would need to be addressed on a site-wide basis, rather than through the use of drop-in applications. This approach inevitably has cost implications, not least the potential need for producing updated reports and the administrative burden of needing to notify every landowner affected by the redline of the original application (which could include individual plot purchasers in respect of large-scale residential sites).

Where material changes are required, the ruling suggests that these need to be done on a site-wide basis as opposed to a series of changes for different parts of a site

These key points demonstrate how important it is for developers to be clear about their plans from the outset. Where material changes are required, the ruling means these must be done on a site-wide basis as opposed to a series of changes for different parts of a site.

There are statutory provisions in place that allow developers to make certain changes, and developers should consider whether they would be able to implement changes to their original planning permission through sections 73 and/or 96 of the Town and Country Planning Act 1990, which may save them from having to submit an entirely new application.

The Hillside decision demonstrates the need for the careful drafting of planning applications and the importance of including sufficient areas of flexibility right from project conception. By including this flexibility, developers will be able to reduce the risk of having any subsequent changes to their plans classed as “material”. While it is likely this decision will be further tested within the courts, it is important for developers to protect themselves as best they can and ensure that, when seeking to make changes to permissions already granted, these changes are not incompatible with what has gone before.

Paul Wakefield and Anna Cartledge are both partners at law firm Shakespeare Martineau