The Court of Appeal has handed down judgement in the latest instalment in a series of legal challenges against various planning permissions for a solar farm site at East Wellow in Hampshire. The history of this site is complex but the judgements provide useful authority on the position regarding variation of planning conditions under Section 73 of the Town and Country Planning Act 1990 (TCPA) and incompatibility of overlapping planning permissions.


To unpick how the planning permissions on this site have evolved since 2017, the below timeline provides useful background (click on each date below to expand and read more):

July 2017 (Original 2017 Permission)

Planning permission was granted for the installation of a ground mounted solar farm on a site extending to 70 hectares of agricultural land.

Description – ‘The installation of a ground mount solar park to include ancillary equipment, inverters, substation, perimeter fencing, CCTV cameras, access tracks and associated landscaping’

July 2019

Section 73 application granted: 

“to allow site levelling to accommodate the DNO substation compound footprint, the installation of a DNO Substation compound with associated equipment and infrastructure and connection to the 132kV overhead line including compound enclosure fencing and additional solar PV panels”.

June 2020

July 2019 permission quashed by consent as ultra vires. The development for which the permission was sought under the section 73 application was different from that permitted by the Original 2017 Permission in that it was to comprise a large DNO substation with a DNO compound.

November 2020

Applications for conditions to be discharged including scheme of noise mitigation (condition 16) and details and location of the 33kV substation (condition 15) submitted in January 2020. Discharges granted in June 2020. Discharges challenged. NMA granted in November 2020 to reconcile permission with discharge of condition 16 (noise). JR claim refused in January 2021.

May 2021 (2021 Substation Permission)

Separate planning permission granted for installation of a DNO 132kV electricity substation, ground mounted solar panels, ancillary equipment, infrastructure and access on 6.78 hectares of land located within the original site. Permission challenged. NMA for condition 15 granted to resolve one ground, other ground dismissed but permission granted for Court of Appeal.

April 2022 (2022 S73 Permission)

Planning permission granted under section 73 to vary conditions attached to the Original 2017 Permission, the effect of which is to change the site layout and design allowing the solar farm permitted by the Original 2017 Permission to operate in tandem with the 2021 Substation Permission.

September 2023

2022 S73 Permission (varying the Original 2017 Permission) quashed on the basis of a conflict between what was permitted in the original permission and what condition two in the 2022 permission required.

December 2023

2021 Substation Permission upheld by Court of Appeal and challenge dismissed on the basis that the officer was not obliged to explain the incompatibility between the two proposals as a mandatory material consideration.

September 2023 Judgement: the extent of Section 73

Mr Justice Morris in his High Court judgement quashed the 2022 S73 Permission as being ultra vires section 73 TCPA. In reaching his decision the Judge relied on the case of Finney and held that there are two distinct restrictions on the power of the LPA to vary conditions under section 73 TCPA:

  1. A section 73 permission must not "introduce a condition which creates a conflict or is inconsistent with the operative wording of the existing original planning permission and its conditions."
  2. A section 73 permission must not "fundamentally alter" the development permitted by the original permission.

The Judge concluded that applying restriction 1, "Condition 2 of the 2022 Permission is inconsistent with and in conflict with the operative wording of the Original Permission". This conflict arose because the operative wording of the Original 2017 Permission allowed a substation to be constructed, however condition 2 required strict conformity with the approved plans and because the 2022 S73 Permission removed the substation element from the plans there was an inherent tension between the operative wording (permitting a substation) and the conditions (not permitting a substation). Applying restriction 2, on the basis that the Judge found the 33Kv substation to be a "central part of the development…the removal of the 33kV substation, and the prohibition upon its construction in the 2022 Permission, constitutes a fundamental alteration of the development permitted by the Original Permission." On this basis, the 2022 S73 Permission was found to be unlawful.

December 2023 Judgement: Incompatibility as a material consideration

The judgement handed down by the Court of Appeal in December dismissed the challenge to the 2021 Substation Permission, which was overlapping and inconsistent with the Original 2017 Permission. The challenge had centred on whether "the fact that the 2021 permission was incompatible with the 2017 permission (and hence that there was a risk of breach of planning control) was something that was so 'obviously material' to the 2021 permission as to require consideration".

Whilst acknowledging the position in Hillside (that a planning permission is not to be construed as authorising further development if at any stage compliance with the permission becomes physically impossible), the Court of Appeal held that there is nothing in the Hillside judgement or elsewhere which would support the proposition that the incompatibility between a previously granted planning permission and an application seeking permission for a different scheme is a mandatory material consideration in the decision being taken.

Moreover, the Court of Appeal found that "the planning system does not preclude the possibility of a number of applications for planning permission being made and granted for different developments on the same site. It accepts the granting and co-existence of mutually incompatible permissions, one or more of which may prove incapable of lawful implementation, whether in whole or in part, unless the incompatibility can be defeated by a further grant of permission under section 70 of the 1990 Act, or section 73".


A distinction can be drawn between (1) a Section 73 Permission which cannot be granted such that it would create a conflict with the original planning permission or fundamentally alter the development permitted by the original permission, and (2) a Section 73 Permission which can be granted even if it is inconsistent with an earlier planning permission. Further, this inconsistency need not be considered by the LPA in making their determination of whether to grant permission. If the inconsistent permission is granted, it would be the developer's choice whether to then implement it noting the potential implications on the validity of the previous permissions.

Where does this leave the developer now? The Original 2017 Permission and the 2021 Substation Permission remain intact following the challenges, however the problem remains that these two permissions are not consistent with each other and so the developer cannot fully implement the two permissions in tandem.

The law is likely to keep evolving in this area with the introduction of new Section 73B into the TCPA 1990 through the Levelling Up and Regeneration Act 2023. This introduces a new power for LPAs to vary a planning permission provided that its effect "will not be substantially different from that of the existing permission". 

This article is for general information only and reflects the position at the date of publication. It does not constitute legal advice.