Changes now – Supreme Court rules on drop-in planning applications

Making variations to planning permissions as a scheme evolves is rarely a straightforward process, particularly where the changes go beyond the scope of non-material or minor material amendments.

One tool that has been used extensively to achieve variations is the “drop-in” planning application where a new consent is granted for an area that overlaps with the original permission. The conditions and any planning obligations for the new consent are tailored to ensure that they dovetail with those associated with the original permission.

However, reliance on this process has been brought into question as a result of litigation concerning a site at Balkan Hill, near Aberdyfi in Snowdonia.

The Hillside litigation

This site has a long and controversial planning history.

Planning permission was granted in 1967 for an estate of 401 dwellings. The planning permission was accompanied by a master plan, which specified the location of each house and the layout of the roads serving the development.

However, the requirements of the 1967 permission have been more honoured in the breach as of the 41 houses that have been built, none of them reflect the requirements of the master plan.

In practice, the developers have relied on a series of separate planning applications to develop the site out. In 2017, the Snowdonia National Park Authority decided that enough was enough and informed the owners of the site, Hillside Parks Limited, that it could no longer continue to build out in accordance with the 1967 permission as it was not physically possible to carry on with the development in a manner consistent with the master plan.

This prompted Hillside to take High Court proceedings seeking declarations that the 1967 permission remained valid and could be carried out to completion as set out in a High Court declaration obtained back in 1987. This had stated that the 1967 permission could still be lawfully completed in accordance with the master plan “at any time in the future”.

In contrast to the 1987 High Court declaration, both the High Court and the Court of Appeal decided that that development pursuant to the 1967 permission could not now lawfully be continued. The Supreme Court has now endorsed this conclusion.

The Supreme Court decided that the effect of the 1967 permission was to authorise development as an integrated whole – rejecting Hillside’s argument that where planning permission is granted for multiple units, the permission should be interpreted as authorising a number of discrete acts of development.

Accordingly, the starting point for interpreting a planning permission for a multi-unit development is that it does not authorise a set of permissions to construct each individual element of the scheme. It is important to note that the Supreme Court acknowledges that a planning permission may include clear express provisions that provide that individual elements are severable – more of which later.


The judgment provides helpful guidance on issues arising from overlapping permissions:

Pragmatic Pilkington

The Supreme Court has endorsed the so called “Pilkington” principle – with a health warning. Pilkington provides that a planning permission does not authorise development if and when, as a result of physical alteration of the land to which the permission relates, it becomes physically impossible to carry out the development for which the permission was granted – without a further grant of planning permission.

However, the Supreme Court stressed that the Pilkington principle should not be taken too far. The benefit of a planning permission will not be lost if there are minor rather than material departures from it and this is particularly relevant when considering changes to large multi-unit developments.

Abandonment abandoned

The Supreme Court rejected Hillside’s argument that the Pilkington principle was rooted in a principle of “abandonment”, i.e. that the right to develop land under a planning permission will be lost if a landowner acts in a way, which would lead a reasonable person to conclude that the right has been abandoned. The Court confirmed the general principle that there is no scope in planning law for a planning permission to be abandoned mid development.

All is not lost

The Supreme Court expressed the view that if a development cannot be completed fully in accordance with the planning permission, then this does not render everything built unlawful – even in relation to a single building. This was a question left open by the Court of Appeal and if it had gone the other way could have resulted in a raft of retrospective planning applications for works that have already been consented.

Where do we go from here?

So, how does this impact the approach to varying planning permissions? Here are some initial thoughts:

  • If the variation can properly be regarded as a non-material or minor material amendment to the planning permission then specific statutory procedures remain available.
  • When it comes to an existing consent, it is worth reviewing it to see if it does include clear express provisions to the effect that individual elements are severable. For example, if the development is divided into discrete phases this may well be the case.
  • In terms of framing new permissions, in order to build in flexibility, it is worth considering including conditions that make it clear that individual elements are severable.
  • If, as in the case of Balkan Hill, it is apparent that the planning permission authorises development as an integrated whole and cannot be disaggregated, the Supreme Court did offer one possible way forward. This is an appropriately framed additional planning permission that modifies the development, but which covers the whole site.

The developer would then benefit from two separate permissions and could proceed to implement the second. What is being applied for is the modification of the approved development scheme rather than a new “standalone” proposal. This should influence both the supporting information that should accompany the application and also the approach to its determination.

Final thoughts

The Explanatory Notes to the Levelling-up and Regeneration Bill (LURB) suggest that “the existing framework for varying planning permissions is often seen as confusing, burdensome, and overly restrictive by applicants and local planning authorities. Recent case law has compounded these issues”.

While the Supreme Court has gone some way to providing guidance on the approach to variations, uncertainties remain and the case for a more proportionate mechanism to achieve scheme amendments remains compelling.

Whether LURB’s new s73B mechanism to allow non-substantial changes to be made to planning permissions will fit the bill remains to be seen.

Bob Pritchard, Legal Director, Shoosmiths

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