Fallback position: using an existing lawful option

A fallback position is the argument that if permission is refused, something else lawful and less attractive will happen instead, so the council should weigh the proposal against that alternative rather than against the site as it stands today. It is a material consideration under section 70 of the Town and Country Planning Act 1990, and on the right facts it is the most powerful argument available to an applicant.

It also fails more often than it succeeds, and it fails for a reason that is easy to state. The fallback has to be real.

What the argument actually says

The structure is always the same. There exists a development the applicant could lawfully carry out without the permission sought. There is a real prospect that it would be carried out if permission is refused. The effects of that alternative are comparable to or worse than the effects of the proposal. Therefore the harm attributed to the proposal should be discounted by the harm that would occur anyway.

Note what it is not. It is not a threat, and framing it as one damages the case. It is not an argument that the alternative is better. And it does not make policy conflict disappear, it only reduces the weight attached to the harm that flows from that conflict.

Three sources of a lawful alternative come up. Permitted development rights that the applicant could exercise. An extant planning permission capable of implementation. And an existing lawful use that could be resumed or intensified without permission.

The real prospect test

The courts have settled the threshold, and it is lower than most officers assume. A fallback does not have to be probable, likely or the applicant's preference. It has to be a real prospect rather than a theoretical or fanciful one. The Court of Appeal considered this in Mansell v Tonbridge and Malling Borough Council in 2017, where the judgment confirmed that the decision maker must ask whether there is a real prospect of the alternative being implemented, and that this is a matter of planning judgement on the evidence.

Two things follow for the drafting.

A real prospect is evidenced, not asserted. Say who would carry out the alternative, with what resource, on what timescale, and why they would prefer it to doing nothing.

And the lawfulness of the alternative has to be established first. An inspector cannot weigh a fallback that might not be lawful. Where there is any doubt, apply for a lawful development certificate under section 191 or 192 and put the certificate in the appeal bundle. That single step converts the strongest objection into a non-issue.

Permitted development as a fallback

This is the most common version and the most frequently overstated.

The classic case is a householder or small commercial scheme where a larger or uglier version could be built under Schedule 2 to the GPDO 2015 without any application. A rear extension within Class A limits, an outbuilding under Class E, a change of use under Part 3.

For this to work you have to show that the permitted development version is actually available. That means checking, and stating, that no Article 4 direction has removed the right, that the building is not listed, that the site is not on Article 2(3) land where the right is restricted, that the allowances have not already been used by earlier extensions, and that any prior approval the class requires would be obtainable. Drawing the fallback scheme properly, to the same standard as the application drawings, is worth the fee. An annotated sketch invites the response that the fallback was never tested.

Where the fallback requires prior approval, the position is weaker but not hopeless. The argument becomes that the authority would have no proper basis to refuse prior approval on the specified matters, which is a narrower judgement than a full planning assessment.

Extant permissions and implementation

An unimplemented permission is a fallback only while it remains capable of implementation. Check the commencement date against the time limit imposed under section 91, and check whether any pre-commencement conditions have been discharged, because a permission that cannot lawfully be started is not a fallback at all.

A permission that has been lawfully implemented, by a material operation carried out before expiry and in accordance with the conditions, remains live indefinitely and is a much stronger fallback. Evidence the implementation: dated photographs, the building control record, the contractor's records, and confirmation that the relevant pre-commencement conditions were discharged first.

Where the applicant wants to build out an old permission with small changes, the section 96A non-material amendment route sometimes makes the fallback deliverable without a fresh application, which strengthens the real prospect argument considerably.

One caution. Where a site already has overlapping permissions, the interaction between them is a legal question in its own right, and the assumption that an old consent can simply be picked up alongside a new one does not always hold.

Evidencing intention and deliverability

Inspectors distinguish between a scheme the applicant could build and one they would build. The evidence that moves the needle:

• A costed appraisal of the fallback showing it is viable, even if less profitable than the proposal.
• A statement from the applicant, ideally a statutory declaration, that the fallback will be pursued if permission is refused.
• Evidence of capacity: land ownership, funding, a contractor, an existing business that would occupy it.
• Drawings and, where prior approval is needed, a submitted or determined application.
• A timescale, with the constraint that makes it credible, such as a lease expiry or a loan condition.

What weakens it: a fallback the applicant has had available for years and never pursued, a fallback that is obviously worse for the applicant commercially with no explanation of why they would do it anyway, and a fallback described only in the planning statement without a drawing.

How inspectors weigh the comparison

Once the fallback clears the real prospect threshold, the exercise becomes a comparison, and it is specific rather than general.

The comparison runs harm by harm. If the fallback would produce the same loss of daylight to a neighbour, the daylight harm from the proposal carries little weight. If the fallback would produce less harm to the street scene but more overlooking, the two are weighed separately and one does not cancel the other. Inspectors are alert to applicants who use a fallback with one serious harm to excuse a proposal with several.

Weight also varies with likelihood. A fallback that is certain to be built attracts more weight than one that merely passes the real prospect test, and decision letters routinely say so.

And a fallback does not override the development plan. Section 38(6) of the Planning and Compulsory Purchase Act 2004 still requires determination in accordance with the plan unless material considerations indicate otherwise. The fallback is one of those considerations, weighed with the rest.

An illustrative example

An applicant seeks permission for a two-storey side extension refused at officer level for its effect on the street scene. The fallback is a single-storey rear extension of the maximum depth permitted under Class A, plus an outbuilding under Class E covering a substantial part of the rear garden, both drawn to planning application standard. A lawful development certificate under section 192 confirms both are permitted development. The applicant declares, with costings, that they will build both if refused. The inspector accepts a real prospect, finds the garden and outlook effects of the fallback comparable, and allows the appeal on the basis that the street scene harm is outweighed. This example is illustrative and not drawn from a decided appeal.

Drafting the argument in a statement

Give the fallback its own section rather than scattering it through the policy analysis. The order that works:

1. Identify the alternative precisely, with the class, permission reference or existing use relied on.
2. Establish lawfulness, with the certificate reference where one exists.
3. Evidence the real prospect, with the material listed above.
4. Compare effects, harm by harm, using the same headings as the officer's assessment.
5. State the weight you say should attach, and why.

Keep the tone measured. The best fallback sections read as an objective account of what would otherwise happen, not as a bargaining tactic.

Set it out in the planning statement alongside the policy case rather than as an appendix, and make sure the drawings for the fallback are listed in the drawing schedule so they form part of the submitted material. Working out which of the supporting documents the comparison needs, particularly where daylight, noise or traffic effects are in issue, is worth doing before the statement is drafted rather than after.

This is general guidance, not legal advice. A lawful development certificate is the only formal way to confirm that an alternative scheme would be lawful, and you should check the position with your local planning authority or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval. Enter your postcode on PlanScope to see which reports your site needs.