Perhaps the most significant planning case of the decade (so far), Hillside Parks Ltd v Snowdonia National Park Authority [2022] UKSC 30 has once again come to the forefront in the recent Planning Court judgment in R (Dennis) v London Borough of Southwark [2024] EWHC. The question now is what does this case add to the Hillside position, and what is the extent to which this may assist developers going forward?

For more information, visit Anna Cartledges’ blog, highlighting the key issues in the Hillside case.

Background – the position in Hillside

The Supreme Court decision in Hillside was handed down in November 2022. This case has sparked much debate in the planning industry, raising concerns about overlapping planning permissions, the use of drop-in applications, and the severability of planning permissions.

One of the conclusions in Hillside was that planning permissions for multi-phase or multi-unit developments should be treated holistically, such that any new permission authorising development on a site that is materially different from that authorised under an existing permission (making it physically impossible to continue development under the existing permission) would render the existing permission as a whole no longer capable of implementation. There would need to be “some clear contrary indication” to interpret such a planning permission as severable (and therefore still capable of implementation on a particular part or parts of the site).

What did Dennis say?

Dennis provides a useful insight into what the Courts are willing to accept as a ‘clear contrary indication’ that planning permission is intended to be severable (or, rather, what the Courts are not willing to accept).

This case concerned a phased development of the Aylesbury Estate in South London according to an outline planning permission (OPP) and a subsequent s.96a non-material amendment application (NMA) by Notting Hill Genesis, as developer, to “formalise the severable nature” of the OPP. The NMA sought to add the word ‘severable’ into the description of the development of the OPP, with a view to reducing the risk of rendering the OPP incapable of further implementation pursuant to Hillside.

The NMA was granted by Southwark Council on the basis that it was considered to be confirmatory only. Southwark’s reasoning was that the inclusion of phasing on the OPP connoted an “obvious and inherent form of severability”. However, Southwark’s decision was subsequently challenged by a third party (Dennis), who questioned the extent to which such an amendment was indeed ‘non-material’.

The Claimant’s case was that the OPP was not severable to begin with, so the effect of the NMA was not simply to confirm its severability but, rather, to convert a non-severable permission into a severable one, which comprised a material change (and was therefore outside the realms of S.96a). The OPP, the Claimant argued, was granted for the scheme integrated as a whole and not on a ‘mix and match’ basis where the developer could ‘drop in’ a phase physically incompatible with the OPP and yet still be able to rely on the OPP for later phases. The effect of the S.96a application being approved was, therefore, to increase significantly the ‘bundle of rights’ granted by the OPP, disapplying the well-established principle in Pilkington v Secretary of State for the environment [1973] 1WLR 1527 (and subsequently upheld in Hillside) that, where two or more permissions have been granted on the same area of land and development has been carried out under one of those permissions which makes it physically impossible to carry out development approved by another consent, that consent may no longer be relied upon.

The Judge agreed with the Claimant and held that the issue of whether a planning permission should be treated as severable is a matter of construction of that particular consent, but that the mere inclusion of phasing provisions is insufficient to amount to a ‘clear contrary indication’ of severability. Any decision to grant a severed planning permission should be expressed ‘unequivocally’. In this case, the OPP was held to be a single planning permission with provisions for phasing, such that the insertion of the word ‘severable’ comprised a material departure from the development authorised by the OPP. As such, the claim was allowed.

Practical implications

The judgement in Dennis is helpful as it concludes that the use of phasing alone does not render a permission severable. However, it leaves open the question of what would constitute a severed permission (except to say that it should be ‘expressed unequivocally’).

The key message for developers from Dennis is that it is very difficult for an existing permission retrospectively to be deemed severable where the initial application was not submitted and considered on this basis. Crucially, the judgment in Dennis does not indicate that this is impossible, but it does beg the question of what exactly would have been sufficient. It would therefore be prudent for developers to consider the issue of severability at the outset i.e. at application stage, to avoid having to convince the Courts later on, after the event.

For instance, developers could ensure any supporting documents submitted make it clear that the development is intended to be severable. Any aspect of the development that a developer wishes, or may wish in the future, to bring forward as an independent part of the development as a whole should be assessed in planning terms on its own merit.

Such an approach requires an element of forward thinking for developers, which may not always be possible commercially. It also does not assist in respect of current development sites.

There’s no doubt that this issue will continue to be tested in the Courts and that future case law may offer more detailed guidance.

Written By

Published: 5th March 2024
Area: Planning & Environmental

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Rachael acts for both private and public sector clients on all aspects of planning and highways law.

Rachael regularly advises on complex S.106 agreements and infrastructure agreements, including for strategic sites, as well as planning appeals, S.288 challenges and judicial reviews, certificates of lawful use and development, compulsory purchase matters, footpath diversion orders and stopping up orders. Rachael has experience acting for both residential and commercial developers (including social housing developers), local authorities, landowners and funders.

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