R (on the application of Marie-Claire Di Mambro) v East Devon District Council [2026] EWHC 1961 (Admin)
Di Mambro is an important Planning Court judgment on prior approval and the GPDO 56-day rule. It confirms that where a council makes and notifies its prior-approval decision within the statutory period, that decision does not retrospectively turn into deemed consent simply because a court later quashes it.
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- Neutral citation
- [2026] EWHC 1961 (Admin)
- Court
- High Court of Justice, King's Bench Division, Planning Court
- Judgment date
- 6th August 2026
- Judge
- HHJ Russen KC, sitting as a Judge of the High Court
- Case number
- AC-2025-CDF-000090
What Di Mambro decided
The case concerned an application under Class R of the GPDO to change an agricultural building at Shoots Lane in Devon to a flexible commercial use.
East Devon District Council received the application on 5th March 2025 and notified its decision granting prior approval on 29th April 2025. That was within the 56-day period in paragraph W(11) of Part 3 of Schedule 2 to the GPDO.
A judicial review followed. The council conceded that its original officer report had not properly addressed several matters which went to whether the proposal actually fell within Class R at all. A consent order then quashed the prior-approval decision and sent the application back to East Devon for redetermination.
The remaining dispute was whether the quashing order meant the original 56 days had expired without a legally effective decision, so that deemed consent had arisen.
HHJ Russen KC held that it had not.
A quashed decision cannot simply be airbrushed from history
The claimant argued that once the council’s decision had been quashed it should be treated as though it had never existed. On that reasoning there had been no effective notification within 56 days and paragraph W(11)(c) would retrospectively allow the development to proceed.
The court rejected that approach.
An unlawful administrative decision may lose its legal effect when it is quashed, but that does not necessarily mean every event surrounding it is treated as though it never happened. East Devon had in fact made a decision and notified it to the applicant within the required period.
The later quashing could not transform that timely action into an earlier failure to act.
The three paragraph W(11) routes are alternatives
Paragraph W(11) prevents development beginning before one of three events occurs. In broad terms, those are:
- the authority says prior approval is not required
- the authority gives prior approval
- 56 days expire without the authority notifying the applicant whether prior approval is given or refused
The court treated these as true alternatives. Once the applicant had received the council’s prior-approval notice within time, this was a paragraph W(11)(b) case. It did not later become a paragraph W(11)(c) deemed-consent case because the decision was quashed.
This is different from a council simply missing the 56-day deadline
Di Mambro distinguishes cases such as Coventry Gliding Club, where a council had taken a decision within the statutory period but failed to communicate it to the applicant until after the deadline.
Where there is no timely notification, paragraph W(11)(c) can operate according to its terms. Di Mambro involved the opposite situation: the notification itself had taken place within time.
The distinction is between timely action which is later found legally flawed and an omission to notify within the statutory period.
Remitting the application re-engaged the prior-approval process
The consent order did more than quash the original decision. It expressly remitted the Class R application to East Devon for redetermination.
The court held that this re-engaged the paragraph W(11) procedure. A fresh decision period applied to the redetermination, and that period could itself be extended by written agreement between the applicant and the council.
That was what happened. The applicant and East Devon agreed successive extensions while the council sought further evidence about the agricultural use and the agricultural unit.
Deemed consent cannot manufacture a permitted development right
There is a second important point in Di Mambro. Even where the GPDO deemed-consent mechanism does operate, it does not create a permitted development right for a proposal which falls outside the basic definition of the relevant class.
For Class R, the council still had to consider matters including whether the building was genuinely an agricultural building used for the purposes of a trade or business, whether it formed part of an established agricultural unit and whether the cumulative floorspace limits were satisfied.
Those are sometimes described as the headline requirements. If they are not met, the proposal is not permitted development under Class R in the first place.
The court relied on the established distinction between those definitional requirements and the separate matters controlled through prior approval.
The court did not decide whether the Class R requirements were met
This limit on the judgment is important. HHJ Russen KC did not decide whether the building at Shoots Lane actually qualified for Class R.
The original council decision had been quashed precisely because the relevant evidence and statutory questions had not been properly addressed. Those matters were for East Devon to investigate and determine when it reconsidered the application.
Di Mambro is therefore authority on the effect of the quashing order and the prior-approval timetable, not a finding that this particular development did or did not satisfy Class R.
No additional declaration or damages were required
The claimant also sought wider remedies, including declarations and damages based on Human Rights Act arguments.
Those claims did not succeed. The court held that the deemed-consent premise on which they depended was wrong, and the existing quashing and redetermination order already provided the relevant public-law remedy.
The claimant lived some distance from the development and was also held not to have the victim status required for the particular Convention claim advanced.
Why Di Mambro matters
The judgment gives useful certainty where a prior-approval decision is successfully challenged after the original deadline has passed.
A successful judicial review does not necessarily hand the developer an automatic permission which the challenge was intended to undo. Where the original decision was properly notified within time, the application can be remitted and reconsidered rather than deemed consent springing into existence retrospectively.
It also reinforces a point that runs through permitted development case law: the prior-approval machinery only matters once the proposal actually falls within the scope of the permitted development class.
Our wider guide explains prior approval and the separate Class R agricultural building right.
Read the full Di Mambro judgment
The approved Planning Court judgment is held in the Planning Geek case law library. Gold Members can open the protected PDF below.
Di Mambro Case Law Page Updated: 9th September 2026