It is not uncommon for a number of the conditions imposed on a grant of planning permission to include the words “unless agreed otherwise with the local planning authority”. Such words or form of words are known as “tailpieces” and their inclusion is often, but not always, unlawful and can lead to planning permission being quashed (cancelled) by the Courts.
It is entirely understandable why, certainly in the past, such tailpieces were used. They often related to plans that were submitted at the application stage which may later need to be subject to minor amendment before or during the build process. To that extent, they could be seen as the planning authority taking a pragmatic approach to the development process, where the grant of planning permission is the start of the process and not the end.
Back in the good old days*/ bad old days* [delete as appropriate] it would have been standard practice for minor amendments to a scheme to be agreed, often on site, between a developer and the relevant planning officer. However, such informality is/ was fraught with difficulty. Not least, planning permission endures for the benefit of land and all future owners/ occupiers and its associated documents are all part of the public record of what has been approved. If amendments are approved on a hand-shake, how can either the planning authority, or an owner, later prove what has been allowed?
The position was largely clarified in 2009 by the introduction into the Town and Country Planning Act of section 96A. This provided a power for planning authorities to allow, through a formal process, non-material amendments to be made to an existing planning permission. In practice, this is usually by way of an updated version of a plan with the new version being added to the file and the reference to the plan in the conditions being updated. Such a process provides for a formal audit trail of the evolution of a development scheme.
As a matter of process, whether a proposed change is non-material is a judgement for the planning authority, without the availability to appeal that decision or any refusal to allow the change (although such decisions are susceptible to judicial review). Also, since an approval does not create a separate planning permission, the change (if approved) is effective immediately on the date the decision is issued.
The issue with tailpieces, which came before the Courts again in R (James Hall and Co Limited) v City of Bradford MDC [2019] EWHC 2899 (Admin), although a case principally on heritage assessments, is that in theory they could allow a planning authority to agree to dispense with a requirement entirely. If a condition was lawfully imposed on a planning permission, that means that the development would not be acceptable in planning terms without complying with that condition. If an “unless otherwise agreed” provision would allow the development to proceed without such compliance then, logically, the resulting development would be unacceptable and the issue of a planning permission subject to such a condition will be unlawful and susceptible to a challenge by way of judicial review.
The deadline for bringing a planning judicial review (in England and Wales) is six weeks and so any potential challenger will need to act fast.
For a developer/ applicant, care should be taken not to allow the planning authority to issue a planning permission that is a hostage to fortune, even if doing so seems at the time to be a pragmatic move.