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Insights // 10 November 2023

Keeping Planning Permission Alive:  Section 73 and Implementation

Sabah Siddiq and Deena Radi, in our leading Planning & Environmental Law team, explore a recent case.

In the case of R (On the application of) Barbara Atwill v New Forest National Park Authority, Angela Vickers [2023] EWHC 625 (Admin), the High Court held that a s73 application, granting permission for a self-built replacement dwelling to be amended in accordance with certain drawings, was unlawful. Planning permission was granted for the demolition and replacement of a dwelling. A s73 variation, allowing for the as-built replacement dwelling to be amended in accordance with certain drawings, was unlawful because the demolition works had not been lawfully commenced and therefore the planning permission had lapsed.

Facts of the case

Angela Vicker (Interested Party) applied for and was granted planning permission in 2018 for a replacement dwelling, a detached garage with office over and a sewage treatment plant (2018 Planning Permission). Barbara Atwill (Claimant) complained to New Forest National Park Authority (LPA) that the replacement dwelling was not bult in accordance with the 2018 Planning Permission and what had been built was unlawful and caused harm to her and other properties.

In 2020, the Interested Party applied for a variation under s73 of the Town and Country Planning Act 1990, which was refused. The LPA said that the development differed from the approved plans in terms of its positioning, footprint, and dimensions.

In February 2021, the LPA served an Enforcement Notice (EN) on the Interested Party alleging that, the replacement dwelling and the detached garage was not built in accordance with the 2018 Planning Permission in that the location, footprint and size was different to that shown on the approved plans. The EN required demolition of the dwelling and the outbuilding. The Interested Party appealed against the EN, however the appeal was stayed pending outcome of the proceedings brought by the Claimant claim.

In July 2021, the Interested Party applied again for a variation under s73, and this time, the LPA granted permission, on the condition that within two years the as-built dwelling would be amended in accordance with certain drawings (2021 Variation Permission). 

The Claimant challenged the LPA’s decision on the 2021 Variation Permission in the High Court arguing that the planning officer had failed to address whether the 2018 Planning Permission remained extant and, whether the existence of the EN should have been considered in the context that the existing works carried out on the site were unlawful.


The High Court allowed the appeal and the Claimant succeeded on all grounds and failed on one ground.  There are some key points to note from this judgement.

Lawfulness of implementation of permission

Mr Justice Lane states that “The starting point is that, as recognised by the Court of Session in East Dunbartonshire (citing authorities binding in this jurisdiction), when determining if development has commenced, the operations relied on must be ones which can properly be said to be undertaken pursuant to the grant of the planning permission in question. No coherent reason has been advanced for why the determination of the commencement of development for the purposes of section 73(4) should be any different from other situations arising under the town and country planning legislation. The determination does not depend upon the issue of whether the development authorised by the 2018 permission could be implemented or ‘built out’”, East Dunbartonshire Council v Secretary of State for Scotland 1999 S.L.T. 1088, [1998] 11 WLUK 45 considered.

Mr Justice Lane went onto say that “it would be highly anomalous if the decision regarding the commencement of development for the purpose of s73 could be taken on an entirely different basis than  the decision taken on certificate of lawfulness application”, Commercial Land Ltd v Secretary of State for Transport, Local Government, and the Regions [2002] EWHC 1264 (Admin), [2003] J.P.L. 358, [2002] 5 WLUK 853 applied.  Accordingly, the LPA reliance on the demolition works alone was unlawful. Mr Justice Lane stated that it was irrelevant at the time when the Interested Party carried out the demolition, she might not have intended to carry out the unauthorised development and that the intention of the person is not part of the test. (paras 26-46 of the judgement).

Further to this, Mr Justice Lane held that the condition in the variation requiring the as-built dwelling to be amended in accordance with certain drawings was contrary to s.73(5), as the 2018 Planning Permission had not been implemented, which meant that the works that were the subject of the 2021 Variation Permission represented development that required lawful commencement. In purporting to allow those works to take place, the local authority was allowing the development to commence beyond the relevant three-year time limit imposed by the 2018 Planning Permission.

Mr Justice Lane further held that there was overwhelming evidence that the 2018 Planning Permission was no longer implementable, given the serious discrepancies in relation to the as-built building's orientation, height, and appearance and that the LPA had failed to have regards to those factors.  

Materiality of amendments under s73 Application

Mr Justice Lane held that that “An application under s.73 would not founder merely because the proposed change involved more than a minor material amendment. Nor would it necessarily founder if the proposed change involved a ‘fundamental variation to the design ... that was otherwise permitted by the operative part of the permission’", Armstrong v Secretary of State for Levelling Up, Housing and Communities [2023] EWHC 176 (Admin), [2023] P.T.S.R. 1148, [2023] 1 WLUK 305 applied.

However, Mr Justice Lane states that s.73 could not be deployed, if the result would be to change the operative part, or the grant of permission, namely the description of the development contained in the grant, Finney v Welsh Ministers [2019] EWCA Civ 1868, [2020] 1 All E.R. 1034, [2019] 11 WLUK 26 applied and that the wording of the 2021 Variation Permission referred to "details of lighting" and there was a difference in the operative parts or descriptions which was not de minimis or immaterial. Mr Justice Lane held that “In the instant case, lighting was a matter of significance” (paras 62-65 of judgement).


The High Court judgement highlights that when considering implementation of planning permission, any material operations that is relied on must have been undertaken in connection with the planning permission itself and that any subsequent works carried is in accordance with the approved plans of that permission. This was of importance for planning permission to be implemented lawfully.

Further, the judgement reaffirms the position taken in the recent case of  Armstrong mentioned above, which considered the scope of 73 applications, that an application under s73 will not fail merely on the basis, that the changes proposed are considered to be more than a ‘minor material amendment’ or involves a ‘fundamental variation to the design’, which is otherwise is permitted by the operative part of the planning permission.  

Should you require advice and assistance on lawful implementation of planning permission, please do get in touch.

For further information or legal advice, please contact or call 0118 951 6800. 

This article is intended for the use of clients and other interested parties. The information contained in it is believed to be correct at the date of publication, but it is necessarily of a brief and general nature and should not be relied upon as a substitute for specific professional advice.

Sabah Siddiq

Sabah Siddiq

Associate Solicitor, Planning & Environmental Law

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Deena Radi

Deena Radi

Trainee Solicitor

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