Hillside Revisited 2 - Conflicting planning permissions: Reconciling “physical impossibility” with “mere incompatibility”?

1. Introduction

This is the second in a series of Law-Nows relating to the Supreme Court’s judgment in Hillside Parks Ltd v Snowdonia National Park Authority. The first Law Now is available here.

In Hillside,[1] the Supreme Court affirmed and to some extent clarified how to approach overlapping planning permissions.

2. The Supreme Court Judgment in Hillside

A key point from the judgment in Hillside, is the Supreme Court’s analysis of the Pilkington principle.

Pilkington is the leading case on development rights where multiple planning permissions are implemented on the same site: e.g. “Permission A” and then “Permission B”, where Permission B has been implemented and developed and Permission A has not been implemented (or has been implemented but has not been fully built out).

The Supreme Court explained that development rights under Permission A cease to be available if it is physically impossible to develop under Permission A because of the Permission B development. When considering what is “physically impossible”, the correct approach is to consider the whole site covered by Permission A, not just (undeveloped) parts of the site that are still available for development under Permission A.[2]

The Supreme Court judgment suggested that were at least two situations in which physical impossibility would not arise and so a developer might be able to rely on two separate permissions: one concerns “mere inconsistency” between Permissions A and B; and the other concerns the situation whereby development under Permission A would be physically different to the development under Permission B but not in a material way. We consider the “mere inconsistency” point in this Law-Now and will consider the materiality point in a future Law-Now.

The Court distinguished between (a) the “physical impossibility” of carrying out the development authorised by Permission A, and (b) a “mere inconsistency” between Permission A and Permission B. It may be that conditions attached to Permission B would be inconsistent with the Permission A development. If so, Pilkington would rule out further Permission A development only if it were physically impossible to carry out it out.

“Mere incompatibility”, or inconsistent planning conditions, will not be enough.[3] The Supreme Court ruled that a planning permission cannot be relied upon if the land to which it relates has been physically altered (without amendment to planning permission) meaning that it is no longer physically possible to carry out the development granted by that planning permission. The only solution is to obtain an additional planning permission.[4]

Where the dividing line lies between “mere incompatibility” and “physical impossibility” remains unclear. The Supreme Court provides an example of what might constitute “mere incompatibility” (or as they also put it, “mere inconsistency”).[5] They refer to the Prestige Homes case,[6] in which a house was built under a planning permission which included a condition to retain some trees. The Court had to consider whether development under a separate planning permission for second house was lawful, even though it required removal of the trees. The Court decided that it was not physically impossible to carry out the development authorised by the second permission, therefore the second house could be built.

3. Conclusion

The distinction the Court makes is helpful in offering some scope for developers to access development rights either under several permissions on the same land, or when devising consenting strategies to adjust current schemes.

The risk though is the potential loss of valuable development rights, so each situation will have to be carefully analysed. The construction of each permission (conditions, approved plans and supporting information) is key and the judgment provides useful guidance on this point.

[1] Hillside Parks Ltd v Snowdonia National Park Authority [2022] UKSC 30.

[2] Hillside, [41].

[3] Hillside, [43] and [44].

[4] Hillside, [45].

[5] Hillside, [44].

[6] Prestige Homes (Southern) Ltd v Secretary of State for the Environment and Shepway DC (1992) 64 PCR 502.