Kernahan & Anor, R (on the application of) v First Secretary of State & Ors

On a planning challenge under Town and Country Planning Act 1990, a decision-maker need not establish a baseline of existing traffic and calculate cumulative traffic in every case. It is lawful to assess proposed additional traffic alone where that approach is rationally open on the evidence and circumstances.

Planning policies should be read sensibly and generously. A policy concerning later expansion may be an important reminder to consider future impact, without imposing a mandatory exercise that must be expressly addressed in every decision. Nevertheless, a material issue raised in the proceedings must be considered. Reasons must adequately explain how the principal controversial issue was resolved. Where the decision letter leaves substantial gaps on that issue, the decision may be quashed for inadequate reasons.

The claimants sought to quash an inspector’s decision allowing an appeal under section 78 of the Town and Country Planning Act 1990. The permission authorised the renovation of barns for offices and an education centre for the Suffolk Wildlife Trust.

The claimants alleged that the inspector had failed to consider possible future expansion, had assessed traffic without determining the existing baseline and had given inadequate reasons. The court considered whether those matters disclosed an error of law or substantial prejudice through failure to give intelligible reasons under section 288.

1. The court upheld the inspector’s approach to traffic. There is no universal requirement to establish a baseline of existing traffic and add the proposed traffic to it. Depending on the circumstances, an inspector may assess the additional traffic alone, particularly where the baseline is uncertain and difficult to analyse, if it is possible to conclude that the additional traffic would not cause unacceptable disturbance.
2. Policy AP73(viii), concerning subsequent expansion, did not require the inspector expressly to test the development against that provision. Planning policies are to be read sensibly and without a statute-like, nitpicking approach. The provision nevertheless served as a useful reminder that future impact was a relevant matter, and the question of expansion was sufficiently material that it should have been taken into account.
3. On the evidence, the court was prepared to infer that the inspector had considered the possibility of expansion and had accepted the Trust’s explanation that significant staff expansion was unlikely. The claimants therefore failed on the alleged failure to take that matter into account.
4. Under section 288, a decision may be quashed for an error of law or for substantial prejudice caused by failure to comply with a relevant requirement, including the requirement to give intelligible reasons. Applying South Bucks District Council v Porter [2004] 1 WLR, reasons must enable an informed reader to understand how the principal important controversial issues were resolved. The inspector’s decision did not adequately explain her reasoning on future expansion. The application therefore succeeded on that ground alone, and the inspector’s decision was quashed.
5. The claimants were entitled to costs, subject to administrative assessment.