Failed Sequential Tests and the Planning Balance: Lessons from 2026 Case Law
A failed flood risk Sequential Test remains a significant conflict with the National Planning Policy Framework. It is not, however, invariably an automatic legal bar to planning permission.
The 2026 Gladman, North Somerset and Faversham judgments show that a decision-maker may weigh the failure against other material considerations. Any departure from the normal policy approach must be recognised, rationally assessed and supported by adequate reasons.
For project teams, the judgments increase rather than reduce the need for clearly separated planning and technical evidence.
Key technical takeaways
- The Sequential Test remains part of national planning policy in England.
- Its failure should be identified expressly and given appropriate weight.
- Mitigation and lifetime safety evidence do not retrospectively satisfy the Sequential Test.
- Evidence relevant to the Exception Test may still be material to the overall planning balance.
- A strong planning balance requires a quantified and internally consistent flood-risk evidence base.
- Site layout, access, land raising, surface-water management and residual risk should be assessed together.
- The judgments are fact-specific and do not create a general route around the sequential approach.
The current legal and policy position
Paragraph 173 of the National Planning Policy Framework requires a sequential approach in areas known to be at risk now or in the future from any form of flooding.
The objective is to locate development in areas with the lowest probability of flooding. Development should not be allocated or permitted where reasonably available sites appropriate for the development exist in areas with a lower risk.
Paragraph 175 provides a limited exception where the relevant development-plan allocation has already been subject to the Sequential Test or where no built development, access or escape route, land raising or other vulnerable element would be located in the area at risk.
Where the Sequential Test is passed but the proposed development remains in a location where the Exception Test is required, paragraphs 177 to 179 require both limbs of that test to be satisfied.
Source: Ministry of Housing, Communities and Local Government - National Planning Policy Framework: flooding and coastal change
The Planning Practice Guidance continues to state that development should not be permitted where the tests have not been applied as necessary or have not been met.
Source: Department for Levelling Up, Housing and Communities - Flood risk and coastal change
The starting point therefore remains compliance with the sequential approach. The 2026 judgments concern the consequences of policy failure and the lawful exercise of planning judgment. They do not amend the policy itself. For a wider review, see the 2025 flood risk Planning Practice Guidance update.
A connected line of authority in 2026
Gladman: failure should not automatically end the balance
In Gladman Developments Ltd v Secretary of State and Lancaster City Council, the High Court considered the refusal of a proposal for approximately 644 homes.
The inspector had treated the lack of a satisfactory Sequential Test as a clear reason for refusal. The court found that the policy conflict should have been assessed within the wider planning balance rather than treated as an automatic determinant.
The permission was not granted by the court. The decision was quashed so that the planning merits could be reconsidered lawfully.
North Somerset: substantial weight followed by a lawful departure
North Somerset Council v Secretary of State and Persimmon Homes concerned approximately 190 homes at Yatton.
The inspector concluded that the Sequential Test had failed and attributed substantial weight to that failure. The inspector nevertheless found that the proposal's benefits, together with evidence addressing lifetime flood safety, outweighed the harm.
The High Court upheld the decision.
The inspector had not purported to pass the formal Exception Test following failure of the Sequential Test. The same underlying considerations were instead treated as material to the planning balance.
That distinction is critical for technical reporting. A Flood Risk Assessment may support a conclusion on safety and effects elsewhere, but it should not be drafted as though mitigation changes the outcome of the alternative-site exercise.
Faversham: a reasoned policy departure can be lawful
R (Faversham Town Council) v Secretary of State concerned approximately 250 homes at Ham Farm, Faversham.
Flood risk affected parts of the site, including approximately 20 dwellings and the principal access under the relevant tidal scenario. Surface-water flood risk was also considered.
The Sequential Test had not been undertaken. The inspector nevertheless granted permission after assessing mitigation, safety, development benefits and policy conflict.
The High Court dismissed the challenge. The court emphasised that the National Planning Policy Framework is policy rather than legislation. A planning decision may depart from policy where the departure is understood and adequate, rational reasons are given.
The case is significant, but it should not be interpreted as establishing that omission of the Sequential Test is an acceptable project strategy. Current policy and standing advice continue to expect the test to be completed where applicable.
Source: BAILII - R (Faversham Town Council) v Secretary of State [2026] EWHC 1651
Sequential Test failure is not the same as passing the Exception Test
The Sequential Test and Exception Test answer different questions.
The Sequential Test asks:
- Is the proposed development in an area at flood risk?
- Are reasonably available sites appropriate for the development located in areas with a lower probability of flooding?
- Is the chosen area of search justified?
- Have alternative sites been assessed consistently?
The Exception Test asks:
- Do wider sustainability benefits outweigh flood risk?
- Will the development remain safe throughout its lifetime?
- Will it avoid increasing flood risk elsewhere?
- Can flood risk be reduced overall where possible?
Measures such as finished-floor raising, floodplain compensation, flood-resilient construction, attenuation and emergency planning may support the second limb of the Exception Test. They do not establish whether a lower-risk alternative site exists.
The evidence streams should therefore be separated explicitly:
- Alternative-site and policy evidence.
- Site-specific flood-risk and engineering evidence.
- Sustainability and planning-balance evidence.
- The decision-maker's planning judgment.
Urban Water's Sequential and Exception Test reports can be coordinated with the project's technical assessment while retaining this distinction.
Paragraph 11(d)(i) and the strong-reason question
Where the relevant development-plan policies are out of date, paragraph 11(d) applies a presumption in favour of sustainable development unless policies protecting areas or assets of particular importance provide a strong reason for refusing the development, or the adverse impacts would significantly and demonstrably outweigh the benefits when assessed against the framework as a whole.
Footnote 7 includes areas at risk of flooding or coastal change.
Source: Ministry of Housing, Communities and Local Government - National Planning Policy Framework: achieving sustainable development
The judgments indicate that the existence of a flood-risk policy conflict does not itself predetermine the answer to the strong-reason question.
A robust decision should identify:
- the nature and extent of the policy conflict;
- the source, probability and consequences of flooding;
- which parts of the development are exposed;
- the vulnerability of the proposed uses;
- the effectiveness and certainty of mitigation;
- lifetime safety;
- effects on third parties;
- residual risk;
- the proposal's benefits; and
- the weight attributed to each consideration.
Engineering evidence informs several of these matters. It does not determine the final legal or planning judgment.
Technical evidence required for a defensible planning balance
Where an applicant is asking a decision-maker to grant permission despite a disputed or failed Sequential Test, generic statements that the site "can be made safe" are unlikely to provide a strong technical foundation. The Flood Risk Assessment should define and quantify the risk.
1. Establish the risk baseline
The assessment should identify all relevant sources, including where applicable:
- fluvial flooding;
- tidal flooding;
- surface-water flooding;
- groundwater;
- sewer flooding;
- reservoirs, canals or other artificial sources; and
- interactions between sources.
The baseline should use appropriate present-day and climate-change scenarios. Flood outlines should be compared with buildings, access and escape routes, external areas, vulnerable uses, land raising, drainage infrastructure and proposed mitigation.
A competent Flood Risk Assessment should distinguish between the probability of an event and its consequences.
2. Quantify depth, velocity and hazard
Flood-zone classification alone may not adequately describe site safety. Where proportionate, the assessment should examine maximum depths, velocity, rate of onset, duration, direction of flow, flood hazard, blockage, defence overtopping or breach, access conditions and sensitivity to climate change.
Hydraulic modelling may be required where existing datasets cannot resolve these issues at the necessary scale.
3. Test lifetime safety
The assessment period should reflect the expected lifetime and vulnerability of the development. Lifetime safety may depend on finished-floor levels, threshold levels, flood-resilient construction, sleeping accommodation, safe access and escape, refuge, emergency planning, utility resilience and maintenance.
Reliance on evacuation should not be presented as a substitute for avoiding inappropriate exposure where policy requires a safer location.
4. Quantify effects elsewhere
Land raising, buildings and boundary structures can displace floodwater or interrupt overland flow paths. The assessment should demonstrate, where relevant:
- changes in flood extent, depth and velocity;
- volumetric floodplain compensation;
- hydraulic connectivity of compensatory areas;
- changes to flow routes;
- effects on neighbouring land; and
- performance during events exceeding the design standard.
A statement that there will be no increase elsewhere should be supported by levels, calculations or modelling proportionate to the risk.
5. Integrate surface-water drainage
Surface-water management should not be considered independently of the wider flood-risk assessment where overland flow affects the site. The drainage strategy should address the drainage hierarchy, infiltration feasibility, runoff, discharge rates and volumes, climate-change allowances, attenuation, source control, exceedance routes, receiving-system constraints, water quality and maintenance.
Proposed storage or land raising should be checked against fluvial, tidal and surface-water flow paths to avoid conflicting design assumptions.
6. Address residual risk
Residual risk remains after mitigation. Relevant scenarios can include drainage blockage, pump failure, exceedance of the design event, defence failure, loss of power, restricted access, failure to maintain an asset, climate-change uncertainty and events more severe than the adopted standard.
The assessment should explain the consequences of failure, not simply state that failure is unlikely.
Recommended project workflow
Stage 1: Policy and screening review
Confirm whether the Sequential Test is required, the relevant flood sources, vulnerability, development-plan policies, allocation history and likely need for the Exception Test.
Stage 2: Agree the methodology
Define the geographical search area, development type, minimum site requirements, assessment date, site sources, reasonable availability and exclusion criteria.
Stage 3: Develop the technical evidence
Prepare the Flood Risk Assessment, drainage strategy and modelling using a common set of survey levels, design events, climate-change allowances, layout assumptions and mitigation measures.
Stage 4: Test the emerging layout
Move vulnerable development, access and land raising away from the highest-risk areas wherever practicable. Mitigation should follow avoidance and layout optimisation.
Stage 5: Separate technical conclusions from planning judgment
Technical reports should state what the evidence demonstrates. The planning statement should separately address policy compliance, failure, benefits, weight and the planning balance.
Stage 6: Audit consistency before submission
Check that the planning statement, Sequential Test, Flood Risk Assessment, drainage strategy, drawings and access conclusions use the same assumptions and final layout.
Implications for planning applications and appeals
The 2026 judgments provide a potential legal basis for granting permission despite a Sequential Test failure. They do not offer a reliable alternative to completing the test.
A project relying on the planning balance will generally face greater uncertainty because:
- the policy conflict remains;
- the weight attributed to benefits is a matter of planning judgment;
- the adequacy of reasons may be challenged;
- another inspector may reach a different conclusion;
- mitigation can be scrutinised closely; and
- technical uncertainty may reduce the weight given to safety claims.
The strongest strategy remains to demonstrate compliance with the sequential approach wherever possible. Where conflict cannot be resolved, the project team should provide transparent alternative-site evidence, a quantified assessment of flood consequences and a clear distinction between technical findings and the case advanced in the planning balance.
Technical support for flood-risk planning
Urban Water provides flood-risk and drainage engineering support for planning applications and appeals, including Flood Risk Assessments and Sequential and Exception Test evidence where applicable.
The scope should be agreed against the site, development type, available data and planning-authority requirements. Engineering evidence can inform the planning decision, but the final planning balance remains a matter for the local planning authority or inspector.
External sources
- Ministry of Housing, Communities and Local Government - National Planning Policy Framework
- Department for Levelling Up, Housing and Communities - Flood risk and coastal change
- Environment Agency - Preparing a flood risk assessment: standing advice
- Environment Agency - National flood risk standing advice for local planning authorities
- Environment Agency - Flood risk assessments: climate change allowances
- BAILII - Gladman Developments Ltd v Secretary of State and Lancaster City Council [2026] EWHC 51
- BAILII - North Somerset Council v Secretary of State and Persimmon Homes [2026] EWHC 1430
- BAILII - R (Faversham Town Council) v Secretary of State [2026] EWHC 1651
