One of the positive effects of the green revolution is that biodiversity is now a vital factor in many planning decisions. As a High Court case showed, however, it is perfectly possible for an otherwise inappropriate commercial or industrial development to hold the promise of future biodiversity gains.

The case concerned a proposal to quarry about three million tonnes of gravel and sand from a large Green Belt site over a 10-year period. The site would in due course be restored to include new agricultural parkland, woodland areas and hedgerows, together with footpaths and bridleways.

The proposal was highly controversial locally and the local authority refused planning permission, primarily on the basis that the development would harm the openness of the Green Belt. The would-be developer's appeal against that decision to a planning inspector was subsequently dismissed following a public inquiry.

Given the various benefits of the scheme, the inspector acknowledged that it was a finely balanced case. He concluded, however, that the developer had failed to establish the very special circumstances required to justify what he found would be an inappropriate development in the Green Belt.

Crucially, he gave only moderate weight to the acknowledged biodiversity net gains that would be generated by the site's restoration. In doing so, he noted that some of those gains would be required in any event in order to meet national planning policies and future legislative requirements – by that, he meant biodiversity enhancement provisions of the Environment Act 2021 which had yet to come into force.

In upholding the developer's challenge to the inspector's decision, the Court found that he had erred in law in proceeding on the mistaken basis that those provisions would apply retrospectively to any planning permission granted in respect of the scheme. Given the finely balanced nature of the matter, he might have reached a different decision had he not made that error. The decision was quashed.