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Hillside Parks Ltd v Snowdonia National Park Authority – Delivering development by more than one planning permission


United Kingdom

Planning lawyers are well used to reform of the planning system. There are regular changes to planning policy and guidance, permitted development rights as well as recent changes to use classes. There have also been nine Acts of Parliament since 2010 (and one Bill is currently before Parliament) related to planning law. However, it appears nothing gets them as excited as a Supreme Court judgement. Hillside Parks Ltd (Appellant) v Snowdonia National Park Authority (Respondent) (

Hillside relates to a site, in North Wales, with multiple planning consents spanning several decades. The developer of the site was seeking to determine whether the undeveloped elements of a 1967 permission could still be lawfully carried out. The appeal was dismissed.

The judgement reaffirmed the Pilkington principle. This provides that where development has taken place under one permission, whether another planning permission may lawfully be implemented depends upon whether it remains physically possible to carry out the development authorised by the second permission given what has already been done under the first permission.

It is a wide ranging judgement on addressing a number of planning principles, which is worth reading more than once. However, it does not completely resolve matters and does restrict the use of drop-in consents, which were used to avoid submitting consents for the entirety of the original planning permission. The key points for developers are:

  • Where there are multiple consents each permission will need to be considered on its particular facts, but it is now more difficult to use what are termed 'drop-in permissions' on sites where changes need to be made to a masterplan or phase of development.
  • It is a question of interpretation whether a planning permission authorises a number of independent acts of development, each of which is separately permitted by it, or whether it is to be construed as a permission for a single scheme that cannot be disaggregated.
  • Where implementing a subsequent consent means that any of the development authorised by the first permission is physically impossible, the first permission is incapable of further implementation unless the incompatibility is not material in the context of the scheme as a whole.
  • Where part of a development is validly implemented and completed, it does not become unlawful due to implementation of a subsequent consent.
  • As a result, the most legally robust approach may be to apply for a permission for the whole site (including what has already been constructed), which shows the modification. This will mean amending previously submitted documents and additional costs including higher planning fees. I say may, because if parts of the development site have been sold, it will be necessary to include those parts within the planning application. If there are no contractual obligations governing the submission of new applications this could result in uncertainty, increased costs and difficulties in completing section 106 Agreements.  In addition, on a large scale housing development this might mean that residents will be notified of the new application and they will certainly wonder what is going on and how it affects them.
  • It may still be possible to use drop-in applications in conjunction with applications to amend conditions (s.73) as well as non-material amendments (s.96A).
  • Going forward, the use of hybrid (part full/outline) consents for defined phases of development for large sites will be even more attractive.
Finally, as the judgement states, at paragraph 25,"clause 98 of the Levelling-Up and Regeneration Bill currently before Parliament will, if enacted, insert a new section 73B into the 1990 Act giving the local planning authority power to grant a planning permission that varies an existing permission but only if the local planning authority is satisfied that “its effect will not be substantially different from that of the existing permission." Given that the Bill is before Parliament, I think the Government should use its zeal for planning reform to look at the issue of multiple planning permissions on a site and establish a statutory framework for their implementation and amendment and allow for drop-in applications.

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