Local Plans remain the foundation of the English planning system, intended to set out a long-term spatial strategy that meets needs, delivers infrastructure and reflects local priorities. Since the late 2010s, however, the bar for demonstrating deliverability has risen sharply.
The Shift Since 2018
Examination practice has evolved significantly in recent years, reflecting a more exacting approach to deliverability and realism.
- Front-loading of evidence: Inspectors increasingly expect fundamental deliverability questions to be resolved before plan adoption.
- Lower tolerance for uncertainty: Reliance on review mechanisms to address structural viability issues is now routinely challenged.
- Cumulative policy burden: Affordable housing, infrastructure, biodiversity net gain, net zero and design requirements now interact in ways that materially affect development economics.
- Deeper interrogation: Inspectors scrutinise assumptions, cashflow, phasing and land market behaviour, rather than relying on headline appraisal outputs.
Together, these changes mean that viability now sits at the heart of whether a plan is considered effective and justified, not simply whether it is theoretically compliant.
Viability as a Test of Real-World Delivery
For strategic sites and proposed new settlements, viability is increasingly treated as a proxy for whether development will actually come forward in practice.
Inspectors now routinely examine whether the evidence base reflects:
- Land assembly and landowner behaviour
- Delivery risk on complex, long-term sites
- Commercial realities faced by promoters and developers
Evidence that demonstrates theoretical capacity, but fails to engage with delivery dynamics, is generally afforded limited weight.
Infrastructure: Cost, Timing and Funding
Infrastructure remains the most common point of failure in demonstrating deliverability at examination.
Inspector focus typically centres on:
- Whether all necessary infrastructure has been identified and credibly costed
- Whether costs are supported by proportionate technical evidence
- The timing of infrastructure delivery relative to development cashflow
- The realism of assumed funding sources
Particular concern arises where critical infrastructure is assumed to be delivered late in the programme, despite being essential to the functioning of early phases.
Cumulative Policy Impact
Inspectors increasingly assess the combined burden of policy requirements, particularly on strategic growth locations and new settlements.
Testing policies in isolation, or assuming that trade-offs can be resolved at a later stage, is now a vulnerable approach. The cumulative impact of policy requirements is expected to be understood, justified and reflected within the viability evidence at plan-making stage.
Review Mechanisms
Review mechanisms remain a legitimate tool within plan-making, but their role is now tightly constrained.
They cannot substitute for unresolved questions of infrastructure funding, land value or overall policy burden. Where review mechanisms are relied upon to mask uncertainty rather than respond to change, they risk undermining the soundness of the plan.
Case Study: Stroud Local Plan Review
The examination of the Stroud District Local Plan Review provides a clear illustration of the current approach.
Inspectors questioned the realism of assumptions underpinning proposed transport infrastructure and the extent to which cost, funding and delivery risk had been adequately reflected in the viability evidence. The examination was paused to allow further technical and viability work to be undertaken.
Where infrastructure is fundamental to the success of a place, Inspectors increasingly expect viability evidence to engage directly with cost certainty, timing, funding mechanisms and delivery risk.
The Stroud examination demonstrates that strategic ambition alone is insufficient. Deliverability must be supported by credible economic evidence that reflects how development will be delivered in practice.
Common Failings in Viability Evidence
Recurring weaknesses identified through examinations and appeals include:
- Weak or unsubstantiated benchmark land values
- Omitted or notional strategic infrastructure costs
- Limited contingency and risk allowances
- Optimistic assumptions around value growth or absorption rates
- Misalignment between infrastructure phasing and development delivery
Individually these issues can be problematic; in combination they often undermine confidence in overall deliverability.
Evidential Burden
Strong viability evidence for strategic sites and new settlements is typically characterised by:
- Transparent and clearly justified assumptions
- Explicit treatment of risk and uncertainty
- Alignment between policy ambition and economic reality
- Clear linkage between infrastructure, phasing and funding
- A grounded understanding of land and development markets
- Evidence rooted in delivery experience
Conclusion
Plans that engage honestly with viability—acknowledging trade-offs, risk and delivery constraints—are more resilient and more likely to succeed at examination.
Plans that rely on optimism, deferred solutions or incomplete evidence are increasingly exposed. Viability has become not just a technical exercise, but a central discipline in demonstrating that strategic growth can be delivered in practice.