Farnham SANG capacity at Farnham Park is almost gone. Waverley Borough Council’s latest monitoring shows room for just 16 more dwellings as at 1 January 2026, while the council is now considering buying 20.9 acres beside the park for a new Suitable Alternative Natural Greenspace that could provide mitigation capacity for around 439 to 532 homes.
That does not mean the council is buying planning permission for 500 houses. It means something rather more important in planning terms: without enough environmental mitigation capacity, housing that might otherwise be acceptable can hit a legal roadblock before the usual planning balance even gets very far.
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Only 16 dwellings of Farnham SANG capacity remain
The numbers are unusually stark. Waverley’s latest Thames Basin Heaths monitoring gives Farnham Park a total mitigation capacity of 2,184 dwellings. Permissions already allocated against that capacity account for 2,168 dwellings. That leaves just 16.
There are also two dwellings subject to appeal. Waverley says they will only count against the remaining capacity if those appeals are allowed. In other words, the practical headroom could become tighter still.
Waverley describes Farnham Park SANG as a finite resource. Its published position is equally clear about what happens when it runs out: if there is insufficient capacity and an applicant cannot provide or secure an alternative SANG in accordance with the avoidance strategy, planning permission will be refused.
Why does housing in Farnham need a SANG?
The starting point is the Thames Basin Heaths Special Protection Area, or SPA. It covers important heathland across Surrey, Hampshire and Berkshire and supports protected breeding populations including nightjar, Dartford warbler and woodlark.
Most of built-up Farnham lies within the 400 metre to 5 kilometre zone of influence around the SPA. New homes bring more residents and, with them, more walking, dog walking and other recreation. That additional pressure can affect the protected heathland and its birds.
Under the Conservation of Habitats and Species Regulations 2017, a competent authority must assess a plan or project where it is likely to have a significant effect on a European site. Permission can only be given where the authority is satisfied, subject to the limited statutory exceptions, that the proposal will not adversely affect the integrity of the protected site.
For housing around the Thames Basin Heaths, the established avoidance approach combines SANG with strategic access management and monitoring, usually shortened to SAMM. Our guides explain Habitats Regulations Assessment and Suitable Alternative Natural Greenspace in more detail.
What does a SANG actually do?
A SANG is designed to give residents an attractive alternative place to walk, exercise and enjoy nature, rather than simply adding more visits to the sensitive heathland. Natural England says there are now more than 80 SANGs around the Thames Basin Heaths, providing nearly 2,000 hectares of additional or improved greenspace.
The important bit is that SANG is not just a planning contribution with a convenient label. There has to be real land, suitably located and designed, with enough physical capacity to provide the mitigation being relied upon.
That is why capacity is counted. Waverley’s existing Farnham Park resource can only mitigate a defined amount of new population. Once that capacity has been allocated, another developer cannot solve the problem simply by offering a larger cheque.
Can a housing scheme simply pay more if the SANG is full?
No, not if there is no mitigation capacity available to buy into. A financial contribution is the mechanism used to help fund the mitigation, but the payment does not create extra hectares of usable greenspace by itself.
Waverley currently secures contributions towards Farnham Park through a Section 106 planning obligation, including a unilateral undertaking where appropriate. That obligation must be completed before permission can be granted. But the council’s own monitoring makes clear that the underlying SANG capacity remains finite.
This is the practical point for developers: environmental mitigation capacity can become a hard ceiling on housing delivery. If the Habitats Regulations assessment cannot lawfully conclude that adverse effects on the SPA will be avoided, the issue is not cured by how attractive the rest of the scheme might be.
What Waverley is proposing at Hale Road
Waverley and the Ismaili Trust announced the proposal on 28 August 2026. The council wants to acquire 20.9 acres, or 8.45 hectares, off Hale Road adjoining Farnham Park and turn the land into a new SANG.
The Ismaili Trust is the current landowner. This is still an acquisition proposal, not an existing operational SANG.
Waverley’s Executive is due to consider the acquisition on 1 September 2026. The supplementary capital estimate is then expected to go to full Council on 8 September because the amount is above £1 million.
The purchase would also need specific consent from the West Surrey Shadow Authority. The council report says the acquisition will only proceed if planning permission is granted for the SANG use.
The current supplementary capital estimate is £2,055,712. It includes the land purchase and the initial work needed to establish the site as SANG.
The proposed funding mix is £900,000 from the SANG reserve, £373,000 from capital receipts and £782,712 from General Fund working balances. Waverley expects developer contributions to support the creation, management and maintenance of the SANG over time.
Why does Waverley quote 439 to 532 homes?
Waverley’s announcement gives a range rather than a single dwelling figure. That is sensible because SANG capacity is fundamentally based on the population to be mitigated, not an immutable number of front doors.
The Thames Basin Heaths framework uses a benchmark of at least 8 hectares of SANG per 1,000 residents. The original delivery framework assumed 2.4 people per dwelling unless better local evidence was available.
Waverley’s current Farnham Park monitoring uses 1.98 people per dwelling. Apply those different occupancy assumptions to 8.45 hectares and you get roughly the two ends of Waverley’s 439 to 532 home range.
It is a capacity estimate, not a promise that those homes will be built.
The crucial figure is not whether the eventual capacity lands at the top or bottom of that range. It is that a sizeable new mitigation resource could be created where the council currently has just 16 dwellings of unallocated Farnham Park capacity.
Mitigation capacity is not planning permission
A new SANG would remove one potentially serious constraint for schemes able to use it. It would not allocate land for housing, make a proposal policy-compliant, settle highways or design issues, or guarantee that an application will be approved.
Each development would still need to pass through the normal planning process and satisfy the development plan, national policy and all other material considerations. The SANG simply provides the environmental mitigation needed to address one specific protected-site problem.
For anyone promoting residential land around Farnham, that distinction is worth keeping firmly in mind. A planning application can be perfectly capable of being argued on housing, design and policy grounds and still fail if the protected-site mitigation cannot actually be secured.
What happens next?
The first decision is at Waverley’s Executive on 1 September. Full Council is then expected to consider the supplementary capital estimate on 8 September.
Specific consent from the West Surrey Shadow Authority is also required, and the acquisition is conditional on planning permission for the SANG use.
Even after that, the land would need to be established and managed as a compliant SANG before developers could safely treat the new capacity as available.
So, for the moment, Farnham still has a SANG bottleneck. The proposed Hale Road site could be a major part of the answer, but it is not yet an unlocked housing cheque book.
Primary sources: Waverley Thames Basin Heaths SPA and Farnham Park capacity; Waverley acquisition and finance papers; Waverley Hale Road SANG proposal; Natural England on Thames Basin Heaths mitigation; Habitats Regulations 2017, regulation 63
Farnham SANG News Post Created: 31st August 2026
