In R (Heath & Hampstead Society) v. Camden LBC & Vlachos  EWCA Civ 193 the Court of Appeal upheld the order of Sullivan J quashing the grant of planning permission for a replacement dwelling in the Vale of Health on the basis that the Planning Authority had failed to place the correct emphasis on the comparative sizes of the existing and replacement dwellings, despite the considerable visual improvement which Camden considered the new dwelling would create.
The central issue was the interpretation of PPG2 paragraph 3.6, which provides that a replacement dwelling on Green Belt or Metropolitan Open Land need not be inappropriate development “providing the new dwelling is not materially larger than the dwelling it replaces”. Although the proposed replacement building in the present case was around three times the physical size of the existing dwelling, the Council had concluded that it was “not materially larger” because the increase in size would have no material effect on the openness of the Metropolitan Open Land.
In the High Court, Sullivan J held that this was an unlawful approach to PPG2 para. 3.6. Applying the earlier decision of the High Court in Surrey Homes Limited v. Secretary of State for Environment, Transport and the Regions CO/1273/2000 he stated:
“20. However … the exercise under paragraph 3.6 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 dwellinghouse, will depend on the circumstances of the particular case. It may be floor space, footprint, built volume, height, width, etc. But, as Mr Lockhart-Mummery said in Surrey Homes:
” ….. In most cases floor space will undoubtedly be the starting point, if indeed it is not the most important criterion.”
It is one thing to say that in a case where the increase in dimensions is marginal in quantitative terms, some regard may be had to other matters “such as bulk, height, mass and prominence”; it is quite another thing to set consideration of the physical increase in size to one side altogether, and, in effect, to substitute a test such as “providing the new dwelling is not more visually intrusive than the dwelling it replaces” for the test in paragraph 3.6: “providing the new dwelling is not materially larger than the dwelling it replaces.”
The Court of Appeal upheld the order of Sullivan J. Giving the lead judgment, Carnwath LJ held:
“37. … I do not think that the meaning of the word “material”, notwithstanding its use in planning law more generally, can bear the weight which the authority sought to give it. Size as Sullivan J said is the primary test. The general intention is that the new building should be similar in scale to that which it replaces. The Surrey Homes case illustrates why some qualification to the word “larger” is needed. A small increase may be significant or insignificant in planning terms, depending on such matters as design, massing and disposition on the site. The qualification provides the necessary flexibility to allow planning judgment and common sense to play a part, and it is not a precise formula. However, that flexibility does not justify stretching the word “materially” to produce a different, much broader test. As has been seen, where the authors of PPG2 intend a broader test, the intention is clearly expressed.”
David Elvin QC and Charles Banner represented Alex and Thalis Vlachos, the owners of the site, in the High Court and in the Court of Appeal.