Marr Farm Solar: When Green Land Is Re-Labelled Grey, and a Paper Grid Offer Becomes “Proof”

The Marr Farm solar proposal reveals a growing problem in the planning system: policy is not being openly breached, but re-interpreted just far enough to reach a pre-determined outcome. In this case, productive agricultural land is re-described as “grey”, grid uncertainty is waved away as “non-material”, and planning benefits are treated as certain even where the evidence shows they are contingent at best. Taken together, the approach raises serious questions about whether national and local policy are being applied as intended.

1. When “Grey Belt” Is Still Green

The Marr Farm site is not previously developed land, nor is it degraded or low-value countryside. The applicant’s own Agricultural Land Classification (ALC) evidence confirms that **approximately 79 hectares of the site comprise Best and Most Versatile (BMV) agricultural land (Grades 1, 2 and/or 3a)**¹. This is high-quality, food-producing land.Despite this, the officer report places weight on the emerging concept of “grey belt” to soften the policy implications of developing the site.

However, “grey belt” is not a statutory designation, nor is it defined anywhere in the National Planning Policy Framework (NPPF). It is an interpretive concept linked solely to Green Belt policy, not to agricultural land protection².

Crucially, BMV land protection sits outside the Green Belt framework. Re-labelling land as “grey belt” does not disapply NPPF paragraph 180(c), which requires decision-makers to recognise the economic and other benefits of BMV land as a finite natural resource³. Treating productive farmland as functionally “grey” risks hollowing out this protection entirely.

2. BMV Land and the National Policy Test

National policy is clear: where development would lead to the loss of significant areas of BMV land, that loss should be avoided unless clearly justified⁴.

The scale involved at Marr Farm — around 79 hectares — is unquestionably significant.

Local Plan Policy 60 reflects this national approach, allowing loss of BMV land only in tightly defined circumstances, including where no suitable lower-quality alternatives are available⁵. This is a policy test about land quality and availability, not about convenience, profitability, or grid proximity.

However, in the Marr Farm assessment, the conclusion that Policy 60 Part A(1) is satisfied rests heavily on factors such as layout efficiency, landowner willingness, and proximity to a grid connection. These may be commercially relevant, but they are not the policy test. If grid proximity alone is allowed to override BMV protection, then BMV policy ceases to operate meaningfully wherever grid infrastructure exists.

3. When a Grid Connection “Offer” Becomes Proof of Deliverability

The handling of the grid connection issue is one of the most problematic aspects of the officer report. On the one hand, officers cite NPS EN-3, which states that: “the capacity of the local grid network to accept the likely output from a proposed solar farm is critical to the technical and commercial feasibility of a development”⁶.On the other hand, objectors are told that local grid capacity is not a material planning consideration, because grid constraints are a wider national issue.

These two positions are irreconcilable.

If grid capacity is “critical” to feasibility, it is necessarily material to planning judgment.The report relies on a grid connection offer from Northern Powergrid, which has not been placed in the public domain due to commercial sensitivity⁷. While such an offer is a relevant consideration, it is important to be clear what it does and does not,demonstrate.

A grid connection offer:

establishes a queue position, not guaranteed export;

may assume future reinforcement works;

does not guarantee unconstrained or timely export; and does not confirm that the development’s claimed benefits will be realised in practice.Treating a future, undisclosed connection offer as proof of deliverability risks overstating certainty and understating risk.

4. Overplanting and the Inflation of Benefits

The Marr Farm proposal involves overplanting, with a DC:AC ratio of approximately 1.41, while export would be capped at 40 MW AC by condition⁸.

Overplanting is not prohibited in principle, and national policy recognises that it can be appropriate in some circumstances⁹.

However, the officer report accepts the applicant’s claim that all energy generated will be exported, with no “waste” energy.

This cannot be reconciled with the technical reality of overplanting combined with a hard export cap. In practice, one or more of the following must occur:

output is clipped at the inverter;

generation is curtailed by the grid;

or generation is deliberately limited.

Any of these outcomes means that the maximum theoretical generation figures are not guaranteed outcomes. Yet the planning balance appears to treat them as such. This has the effect of inflating the benefits side of the equation, while the harms , particularly the loss of BMV land , are treated as fixed and acceptable.

5. Permanency of Agricultural Land Loss

The proposed operational life of the Marr Farm solar development is approximately 40 years. While the report refers to potential reinstatement, it is well established in planning practice that development of this duration constitutes a long-term and effectively permanent loss of agricultural land for policy purposes¹⁰.

Soil compaction, altered drainage, access tracks, and decades of non-agricultural use cannot be assumed to be fully reversible. Treating such impacts as temporary risks underestimating the true scale of harm.

6. Pre-Judging the Planning Balance

Across the report, a consistent pattern emerges:

benefits are treated as certain, even where they depend on future grid performance;

harms are treated as manageable or reversible, even where policy treats them as permanent; and conditions are relied upon to bridge evidential gaps, rather than to control clearly understood impacts.This approach does not reflect a neutral weighing of evidence. It reflects a planning judgment that appears to have been reached first, with the policy analysis shaped to support it.

Conclusion

Marr Farm is not a case where policy clearly points to approval and objectors are simply dissatisfied with the outcome. It is a case where policy is being stretched, re-labelled, and selectively applied to justify the loss of high-quality agricultural land on the basis of uncertain future benefits.

When green farmland is re-described as grey,when a future grid connection is treated as present fact and when contingent benefits are given decisive weight,the planning system risks becoming a conveyor belt rather than a safeguard. That is not what national or local policy intends and it is why Marr Farm deserves far closer scrutiny.

Footnotes

1. Applicant’s Agricultural Land Classification evidence submitted with the Marr Farm planning application.

2. National Planning Policy Framework (NPPF), December 2024, Green Belt policy and Footnote 7.3. NPPF (Dec 2024), paragraph 180(c).

4. NPPF (Dec 2024), paragraph 180(c) and associated guidance on agricultural land.

5. Doncaster Local Plan, Policy 60 (Protection of Agricultural Land).

6. National Policy Statement EN-3 (2023), paragraph 2.10.22.7. Officer Report, paragraphs 7.50–7.51 (reference to unpublished grid connection letter).

8. Officer Report, paragraphs 7.13–7.18.9. National Policy Statement EN-3 (2023), paragraph 2.10.55.10. Planning appeal decisions and long-established practice treating long-term solar development as permanent loss for agricultural land policy purposes.