What is deliberate concealment in planning?

What is deliberate concealment in planning? This guide explains how intentional deception can prevent reliance on the four- and ten-year enforcement rules, with key case law including Welwyn Hatfield and Fidler, and practical advice on avoiding costly enforcement risks.

PLANNING ENFORCEMENT

Andrew Ransome

2/28/20263 min read

A common belief in planning is this:

“If development goes unnoticed for four or ten years, it automatically becomes lawful.”

While statutory time limits do provide important certainty, they are not a loophole that allows someone to game the system.

Planning law recognises a principle known as deliberate concealment, which can prevent a developer or landowner from relying on those time limits where there has been intentional deception.

Understanding how this principle works — and when it may apply — is essential for anyone considering retrospective planning, relying on the passage of time, or applying for a Lawful Development Certificate.

The usual rule: time limits for enforcement

Under the Town and Country Planning Act 1990 (TCPA 1990), there are statutory time limits for enforcement:

4 years for operational development (e.g. building works) and use as a single dwellinghouse (subject to transitional arrangements).
10 years for other breaches of planning control.

If the local planning authority (LPA) does not take enforcement action within those periods, the development can become lawful. A landowner may then apply for a Lawful Development Certificate (LDC) to confirm that status.

These time limits are intended to provide certainty. But they are not a licence to deceive.

The leading case: Welwyn Hatfield

The modern law on deliberate concealment stems from the Supreme Court decision in Welwyn Hatfield BC v SSCLG & Beesley.**

In that case, the developer obtained planning permission for a barn. However, he had no intention of building a genuine agricultural barn. Instead, he constructed a building that looked like a barn but was internally fitted out and used as a dwellinghouse.

He then occupied it as a home for four years.

After the four-year period expired, he applied for an LDC, arguing that the residential use was now lawful under the statutory time limit.

The Supreme Court rejected that argument.

The Court held that although planning law is a comprehensive statutory code, a fundamental public policy principle still applies: no one should benefit from their own wrongdoing (sometimes called the Connor principle).

Where there has been “positive deception in matters integral to the planning process”, and that deception was intended to undermine the system, a developer cannot rely on the four-year rule.

In short: the law will not reward fraud.

The “straw bale castle” case

A well-known example of deliberate concealment is R (oao Fidler) v SSCLG & Reigate and Banstead BC.**

Here, a developer built a house disguised as a castle and hid it behind straw bales and tarpaulins for four years. The Court of Appeal described this as a “paradigm case of deception”. The intention was clear: conceal the dwelling until immunity was achieved.

Following the reasoning in Welwyn, the developer was prevented from relying on the four-year rule.

Is concealment only about hiding buildings?

No.

In Matilda Holdings Ltd v SSCLG the High Court confirmed that deliberate concealment can arise even where a use is physically visible. It is not limited to physically hiding a building behind barriers.

Importantly:

There is no separate “exceptional” or “egregious” test.
The four specific factors discussed in Welwyn do not all have to be present.
Each case turns on its own facts.

The question is whether there has been positive deception connected to the operation of the planning system.

What is not deliberate concealment?

The courts have made clear that this principle should only apply in serious cases.

Simply:

“Keeping a low profile”
Failing to draw attention to a breach
Hoping the council does not notice

…will not automatically amount to deliberate concealment.

The deception must be active and directed at undermining the planning process itself.

Later cases, including Jackson v SSCLG; Bonsall v SSCLG, confirm that the Welwyn principle continues to operate alongside the statutory Planning Enforcement Order regime. The courts have rejected arguments that concealment can only be addressed through that procedure.

Why this matters in practice

For property owners and developers, the risks are significant:

You may invest heavily in works believing they will become lawful through passage of time.
You may apply for an LDC after four or ten years.
The LPA may refuse the certificate on the basis of deliberate concealment.
Enforcement action may still follow — even after the usual time limits.

In addition, if a decision-maker considers that your conduct has been disreputable (even if not quite at the Welwyn threshold), it may reduce the weight given to your evidence.

Practical advice

If you are considering relying on the four- or ten-year rule you should obtain professional advice before proceeding.

Planning law does provide certainty through statutory time limits. But those protections are not available where the system has been deliberately deceived.

If you are facing enforcement action or considering applying for a Lawful Development Certificate, careful legal and evidential strategy is essential. Early advice can often prevent a costly and stressful dispute later on.

About me

Andrew Ransome is the planning director at ADP and is a chartered member of the RTPI, with over 22 years of town planning experience.

Andrew has extensive experience offering strategic planning solutions to challenging projects in both rural and urban settings. Follow him on Linkedin.