The appropriate focus and detail of evidence required to support a local plan will vary from for different places and will require planners to make professional judgements to assess an area and develop a plan appropriate to its own circumstances. We have produced some top tips for producing a proportionate and robust evidence base which we hope you fid useful. PAS published a more detailed note setting out advice and matters to be considered when collating evidence in support of a local plan in February 2020. We also have webpages on Project Managing the Local Plan, Sustainability Appraisal and Monitoring.
Preparing a Local Plan is a complex project. It involves a number of stages and associated tasks. One of the fundamental tasks is the scoping, preparation and creation of up-to-date evidence. A clear, concise relevant and proportionate evidence base is a cornerstone of efficient and sound plan-making. The National Planning Policy Framework (NPPF) sets out the requirement for the preparation and review of all policies to be "underpinned by relevant and up-to-date evidence" This is arguably the most resource intensive and time-consuming part of the plan making process so we have made some top tips to help.
Evidence Base Top Tips
Be clear on the scope from day one and be explicit about what the plan is (and isn’t) doing - A clear scope saves time, money and helps identify key evidence base needs.
Critical evidence depends on local circumstances—housing, employment, green belt, transport, and so on.
Early on, rank which evidence strands are essential.
The chapters of the National Planning Policy Framework can guide you when checking what is up to date.
Review any existing evidence base to see how relevant it remains and whether it is still up-to-date.
Start with what evidence you already have. Ask: Why is this evidence needed? What decision will it inform
Update evidence so it is fit for purpose
Some evidence (for example, a strategic housing market assessment) can go out of date after two years, especially if it involves market signals or land availability.
Other evidence (such as a landscape character assessment) might remain current for longer, but you still need to confirm it reflects local conditions and any changes to these.
Be clear about evidence — quality over quantity
Avoid commissioning evidence “just in case”
This should be part of your overall approach to Project Managing the Local Plan.
Identify new or updated evidence needed, plus time, budget, and staff capacity.
Include milestone dates for commissioning and final reports, along with risk management; for example, what if data is delayed?
Set clear governance and decision-making routes
Define roles and responsibilities across the organisation
Get senior and political (cross party) buy-in early
Identify risks early — and keep them live
Carry out an early risk assessment
Maintain a live risk register
Typical risks:
Resources and skills gaps
Political change
Evidence delays
Plan mitigation, not just identification
Be realistic about time and resources
Build a detailed project plan
Match tasks to actual staff capacity
Allow time for:
Evidence commissioning
Engagement
Decision-making
Build in contingency — things will slip
Be flexible and creative with resources
Don’t assume the planning team does everything
Look across the council for skills and support
Consider:
Shared services
External support
Temporary capacity
Challenge “we’ve always done it this way”
Engaging with stakeholders on core strategic matters helps you shape the right evidence and supports your evidence on cross boundary or strategic level issues. #
Examples of key stakeholders are : neighbouring authorities, county councils, infrastructure providers, and local communities.
Engage early and align with wider strategies, including any Strategic Development Strategies being prepared.
Corporate priorities
Other council strategies
Avoid policy silos
Take Cooperate seriously
Build it into the project plan
Assign clear responsibility
Keep good records of engagement and outcomes
If there are key corporate priorities (for example, a climate strategy), ensure this feed into your plan’s evidence.
Engage other departments early—housing, regeneration, or economic development—to reduce duplication, save money on preparing evidence and to gather local intelligence.
Remember Planning is a key enabler of a council's corporate strategy, vision and objectives. The Local Plan needs to be the delivery vehicle for what the council, and its members, want to achieve.
Use the PAS Project Management toolkit for the current system and the PAS Project Initiation Document (PID) template for the new plan system. These have been designed to help you map out the evidence base, its sequencing and drawing together to reach critical plan stages.
Our “Evidence for Plan Making” advice note (February 2020) includes an Evidence Base Prioritisation and Audit template and an Evidence Action Plan.
A simple process diagram can help you see how evidence aligns with each plan stage.
Regularly audit which evidence is complete, which is in progress, and what is still outstanding.
Make sure your procurement briefs are clear about scope, outcomes, and format.
Think about whether this can be achieved in-house with a lighter touch external critical friend review, rather than a wholesale external commission
Agree realistic timetables and deliverables with consultants.
Avoid external studies becoming overly long and complex
Avoid “gold-plating”: only commission what you genuinely need to support the plan.
A common pitfall is out-of-date or poorly sequenced evidence, especially if it must link with strategic studies or cross-boundary matters.
Use the PAS Project Management Tool to help sequence the strands of evidence base.
Do not jump to commissioning, for example, infrastructure modelling before you know your potential spatial options.
We know that Sustainability Appraisals and Strategic Environmental assessments are expected to not form part of the new plan making system and eventually be replaced by Environmental Outcome Reports. It is still really important to have an evidence base that considers the impacts, mitigations and alternative approaches to be developed and inform the plan.
The evidence base on impacts, mitigations and alternatives (such as Strategic Environmental Assessment, Sustainability Appraisal and Integrated Assessment) should inform policy choices and site selection, not be a bolt-on at the end. There is always a need to show how the evidence base has informed the plan development, this can be achieved effectively through things like topic papers.
Our PAS guide to better Sustainability Appraisal offers practical tips.
Make sure the evidence base on impacts, mitigations and alternatives is integrated at each key plan-making stage to shape options and solutions.
The evidence is not tested in isolation; the inspector will focus on whether it justifies your plan.
Signpost your main evidence documents in footnotes or supporting text so they are easy to find.
If you choose not to accept a consultant’s recommendation, record why—examiners look for clarity on such decisions.
PAS published a note in 2020 setting out advice and information that should be considered when collating evidence to support a local plan. It is designed for LPAs to use themselves but we can work with local authorities to use it as a “critical friend”. We are helping councils with an evidence base audit (what’s still relevant, needs updating etc.), reviewing the overall approach to scoping, creating and interpreting the evidence base, and providing a view on its fitness for purpose. Plus reviewing and providing advice on specific/specialist evidence base topics or providing advice to stakeholders e.g. members. Many councils find the PAS support a useful and complementary addition to their plan making activity: Support for Plan Making, Review and Update.
In 2024, we published a guide to better Sustainability Appraisal to provide tips and good practice on this aspect of plan-making. We also have a Monitoring webpage - see side bar for links.