R (on the application of Wyatt) v Fareham Borough Council [2022] EWCA Civ 983
Wyatt nutrient neutrality is an important Court of Appeal judgment on Habitats Regulations assessment for housing in the Solent.
The court upheld Fareham Borough Council’s use of Natural England’s nutrient methodology. The legal standard was no reasonable scientific doubt that the protected sites would not be adversely affected, but that did not require absolute certainty or the most precautionary possible assumption at every individual step of the calculation.
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- Neutral citation
- [2022] EWCA Civ 983
- Court
- Court of Appeal (Civil Division)
- Judgment date
- 15th July 2022
- Judge
- Sir Keith Lindblom, Senior President of Tribunals, Lord Justice Singh and Lord Justice Males
- Case number
- CA-2021-000658
What Wyatt nutrient neutrality decided
The case concerned permission for eight homes at Egmont Nurseries in Warsash. New housing around the Solent was subject to concerns about additional nitrogen reaching internationally protected habitats.
Fareham carried out an appropriate assessment using Natural England’s then-current methodology. That included assumptions about household occupancy and land use, a 20% precautionary buffer and on-site mitigation through a wetland.
The Court of Appeal dismissed the challenge on every ground.
No reasonable scientific doubt does not mean absolute certainty
The Habitats Regulations require the competent authority to be satisfied that a plan or project will not adversely affect the integrity of the protected site.
Wyatt confirmed that the familiar “no reasonable scientific doubt” standard is rigorous, but it is not a demand for absolute certainty. Scientific assessment inevitably involves evidence, assumptions and expert judgment.
The methodology is assessed as a whole
The claimant attacked individual parts of the nutrient calculation, including the national average occupancy figure of 2.4 people per dwelling, assumptions about previous land use and the 20% buffer.
The Court of Appeal rejected the idea that every separate input had to be the most precautionary figure conceivable. The question was whether the assessment as a whole, using the best scientific knowledge available, provided a sufficiently precautionary and robust basis for the conclusion.
Natural England’s advice could carry substantial weight
Natural England is the statutory nature-conservation adviser. The council was entitled to give substantial weight to its technical methodology and advice.
A competent authority is not legally bound to follow Natural England, but if it proposes to depart from clear expert advice it may need cogent reasons. Conversely, reliance on that advice does not remove the authority’s own responsibility for the appropriate assessment.
A reasonable worst-case scenario is not always mandatory
The court rejected a general legal rule that every appropriate assessment must adopt a quantified worst-case scenario for each variable. The precautionary principle is applied through the assessment as a whole.
Expert judgment can also support a precautionary buffer without the buffer having to emerge from a precise mathematical formula.
Later evidence can explain but not replace the original reasoning
The council relied in the litigation on expert evidence explaining the technical basis of the assessment.
The Court of Appeal held that later evidence can legitimately elucidate or amplify the reasoning which was already present at the time of the decision. It cannot contradict the original assessment or invent an entirely new reason which the decision-maker never had.
The development-plan challenge also failed
The claimant argued that the scheme conflicted with individual development-plan policies and that the officer report had therefore misapplied section 38(6).
The court rejected a rigid two-stage formula. The development plan must be read as a whole, and an officer report is read fairly with realism and common sense. The council was entitled to conclude that the proposal accorded with the plan overall despite conflict with individual policies.
See our guide to planning officer reports.
The Solent methodology in Wyatt is not a permanent formula
Wyatt examined the evidence and Natural England methodology available for this decision in 2020. Nutrient-neutrality evidence, catchment strategies and technical guidance can change.
For current practice, use Planning Geek’s guides to Habitats Regulations Assessment and nutrient neutrality rather than copying the figures used in this case.
Read the full Wyatt judgment
The full Court of Appeal judgment is held in the Planning Geek case law library. Gold Members can open the protected PDF below.
Wyatt Nutrient Neutrality Case Law Page Updated: 10th September 2026