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s73 Applications: (Not so) minor material amendments

In January 2023, a decision was handed down in the case of Armstrong[1] concerning the extent to which a s73 application may vary an original permission.

Planning permission was granted for the construction of one dwelling.  The applicant sought to amend the approved drawings by way of a s73 application.  The approved development consisted of a modernist building but the revised proposals were for an alpine lodge style dwelling.  The Council refused consent and the inspector agreed with the Council, stating that the development “would result in a development that would differ materially from the approved permission”.  As such, in the inspector’s view, the application fell beyond the scope of s73 of the Town and Country Planning Act 1990.

Importantly, it was agreed by all parties that the proposed development in the s73 application did not conflict with the description of development for which permission was originally granted.

Legislative background

The Act identifies two key methods of varying a planning permission:

  • non-material amendments, under s96A of the 1990 Act
  • by varying conditions, under s73 (or s73A if work has started under the original consent) of the 1990 Act.

National planning practice guidance (PPG) refers to s73 applications as including “minor material amendments”.  The PPG acknowledges that there is no definition of “minor material amendment” but states “it is likely to include any amendment where its scale and/or nature results in a development which is not substantially different from the one which has been approved”.


The issue in the case was whether s73 of the 1990 Act could be used to amend a condition resulting in “a fundamental variation to the design” of the single dwelling, providing it was permitted by the operative part of the planning permission.  The judge held this was within the remit of s73 for a number of reasons, including:

  • There in nothing within the 1990 Act that limits the application of s73 to minor material amendments. By contrast, there are provisions preventing extensions of time and amendments under s96A are expressly limited to non-material amendments.  If it had been Parliament’s intention to limit the scope of s73, this would have been set out within the legislation.
  • It is well established (see Finney and Arrowcroft) that a s73 cannot be used to vary or a condition where the resulting condition would be inconsistent with the operative part of the planning permission. Providing there is no conflict with the operative part of the decision, the exact purpose of s73 is to vary a condition.
  • Although s73 may be used to vary conditions which can result in substantial changes to the original scheme, it does not automatically mean that the application will be granted. The application must be determined on its planning merits – which will involve consideration of whether the change (be it minor or fundamental) is acceptable in planning terms.

The judgement considers that the reference to “minor material amendment” within the PPG is “liable to confuse”.

The case helpfully confirms that a s73 application can be used to obtain a new permission varying conditions of an original permission so as to allow fundamental variations to a scheme - providing that there is no conflict with the operative part of the permission.

[1] [2023] EWHC 176 (Admin)

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