The Thirty-Year Promise: Auditing Where Your Council's Nature Offsets Actually Land
Every planning authority in England now runs a market in nature. Since biodiversity net gain became mandatory — for major developments in February 2024 and for smaller sites that April — councils have been approving schemes on the promise that habitat lost to tarmac and drainage will be replaced, improved or recreated elsewhere. At least ten per cent, for thirty years, secured by condition and monitored by someone.
The question for campaigners is simple. Where is it?
A ledger is not a habitat
The mechanics are easy to describe and hard to police. A developer must produce a biodiversity gain plan, measured by Defra's statutory metric. They can deliver the gain on site, buy units from an off-site habitat bank, or — as a last resort — purchase statutory credits from Natural England. The first option is visible. The second is where the accounting gets creative. Credits can be generated miles away, on land the developer does not own, by a third party who may never have met the planning committee. The gain is registered, the loss is local, and the two are connected by a spreadsheet.
For communities staring down a contentious application, that spreadsheet is the campaign document. It is also, in most councils, poorly kept.
What the council holds — and what it hides
The national biodiversity gain site register is maintained by Natural England. But your council holds the operational paper trail: the planning conditions, the gain plans, the section 106 agreements, the habitat management and monitoring plans, and its own records of which permissions rely on which offset. It is under no obligation to publish most of this in a searchable form.
A Freedom of Information request should therefore ask for the following, for the past three years:
- every planning permission granted with a biodiversity net gain condition, including the application reference and the date of decision;
- the biodiversity gain plan and the completed statutory metric spreadsheet for each;
- the habitat management and monitoring plan, and the name of the responsible body contracted to deliver it;
- the off-site register entry number and the location of every off-site unit purchased;
- the section 106 agreement or condition securing thirty years of management and its funding;
- the council's own enforcement log for BNG conditions.
Ask for the data in CSV, not PDF. Ask for the register in its native format. Refusal on grounds of commercial confidentiality is common; challenge it. The location of a habitat bank is a planning fact, not a trade secret.
Follow the credit to the ground
Once you have the list, test it. Take the five largest off-site purchases in your area and plot them on a map. Compare the registered habitat type against what is actually there. Use MAGIC, the government's mapping service, and historic aerial photography. A field recorded as "modified grassland" that has been intensively grazed for twenty years is not a new wildflower meadow, whatever the metric says.
Then ask three questions of each site:
- Additionality. Was the habitat already in good condition before it was banked? If so, the gain is fictional — a rebadging exercise dressed as compensation.
- Proximity. Is the offset within the same national character area, or at least the same local nature recovery strategy area? A credit bought two counties away may satisfy the metric while doing nothing for the species and habitats your planning committee was told would be protected.
- Security. Who owns the land, who manages it, and what happens if the management company folds? Thirty years is a long time in the life of a shell company.
The enforcement gap
The uncomfortable truth is that no single body is resourced to check. Natural England registers sites but does not inspect them routinely. The council is the enforcing authority for planning conditions, but planning departments are stretched, and habitat monitoring requires ecological expertise most authorities no longer employ in-house.
That is why the audit must be public. Publish a table of every BNG permission in your area, the offset location, the claimed gain and the evidence status. Send it to your ward councillors, your MP and the local media. Ask the council's scrutiny committee to review the enforcement record. Where a site cannot be verified, say so plainly.
Before the local plan vote
Local plans are being rewritten across the country through 2026, and the forthcoming round of votes will set the spatial strategy for a decade. Biodiversity net gain is now part of the evidence base. If the offsets in your area are paper-thin, the plan's claim to be "nature-positive" is not evidence — it is branding.
Bring the audit to the examination in public. Ask the inspector how the plan's habitat targets will be delivered when the council cannot say where the existing credits are. Demand that the local nature recovery strategy maps the offset sites, not just the aspiration.
The point is not to stop building. It is to insist that when a council signs away a hedgerow, a pond or a patch of ancient woodland, the replacement is real, local and looked after. A ledger is not a habitat. A credit is not a creature. And thirty years is too long to wait to find out that the promise was only ever a number in a cell.
We say enough.
