National green belt policy has been largely consistent since the 1980s. The most recent NPPF perpetuates the principle that ‘openness’ is fundamentally down to an absence of development. It is important to note that green belt is a policy designation, whereas ‘greenfield’ is a distinction as to whether the land has been previously developed or not (i.e. the opposite to ‘brownfield’).
Materially larger
There is no definition in statute or government guidance about what ‘materially larger’ means. However, in an application for a replacement dwelling in metropolitan open land (the equivalent of Green Belt) the Court of Appeal set out the framework and tests authorities should apply in R (Heath and Hampstead Society) v London Borough of Camden [2007]. These are summarised as:
- ‘Materially larger’ is a threshold question involving a mathematical calculation of comparison in size between the existing and that proposed. If the proposal is materially larger, it will amount to inappropriate development;
- The test is tightly drawn to prevent incremental increase; and
- Where there is no significant increase in size, authorities may assess qualitative matters such as design, massing, visual impact or disposition on site.
Affirming the decision of Sullivan J, the Court of Appeal said size “…is the primary test. The general intention is that the new building should be
similar in scale to that which it replaces”.
Drawing on the view of District Judge Lockhart-Mummary QC in Surrey Homes Ltd v Secretary of State for Environment, Transport and the Regions, Sullivan J said “…The exercise…is primarily an objective one by reference to size. Which physical dimension is most relevant for the purpose of assessing the relative size of the existing and replacement dwelling house, will depend on the circumstances of the particular case. It may be floor space, footprint, built volume, height, width etc. But as Mr Lockhart-Mummary said in Surrey Homes ‘…In most cases floor space will undoubtedly be the starting point, if indeed it is not the most important criterion’”.
In his judgment on Heath and Hampstead, Sullivan rejected the submission that ‘materially larger’ should be judged exclusively by reference to floor space, saying that to prescribe a calculation based only on floor space would lead to “…absurd results. One could have equivalent or possibly even reduced floor space, but disposed within a tower-like structure, having far more impact on the Green Belt. It would be a strange result, in my judgment, if an Inspector were debarred from concluding that the proposed structure harmed openness and was inappropriate development”.
The 2010 decision in Feather v Cheshire East Council is also of note (that a basement, although underground, was a material consideration). ‘Materially larger’ is primarily a question of size but that, in deciding which measurements to compare, account must be take of the distribution of dimensions.