In More of the same we reported an appeal case (DCS Number 400-015-923) in which the inspector considered the nature of intensification. This was in relation to a caravan site in Hertfordshire. In so doing he cited R (John Childs) v First Secretary of State and Test Valley Borough Council . In a more recent appeal case in Aberdeenshire (DCS Number 400-030-360), again involving caravans, the reporter set out further relevant case law. She also set out a handy formula for dealing with such situations.
There were, she reasoned, (potentially) two questions for her to decide: first, would there be a definable change in the character of the use of the land from the permitted use if the proposed use went ahead? second (if the answer to the first question was yes), would the change of use be material? She also recognised that any effects of any such change of use, on- or off-site, would only be relevant to the second question.
Here is the case law cited by the inspector:
Cotswold Grange Country Park LLP v Secretary of State for Communities and Local Government  confirms that when planning permission is granted for a particular use, any limitation on the way in which that use is to be exercised must be imposed by condition. The reporter found that the facts of that case had some similarity to the case before her in that the description in the permission at issue referred to the siting of a specified number of caravans within a caravan site, but no condition limited the number of caravans to the number specified in the description. The court confirmed that the description did not limit the number of caravans on the site and that a proposal for the siting of additional caravans raised the question only of whether that would constitute a material change of use from the permitted use.
In Hertfordshire County Council v Secretary of State for Communities and Local Government, Metal and Waste Recycling Limited , the reporter continued, the High Court found that mere intensification of a use of land does not by itself amount to a material change of use if it falls short of materially changing the definable character of the use of the land. And, in Reed v Secretary of State for Communities and Local Government , the Court of Appeal confirmed that this principle would apply to an increase in the number of caravans in a caravan site. Moreover, in Hertfordshire, the court found that, while significant environmental effects, on- or off-site, might be evidence that a material change of use by intensification has occurred, they do not themselves constitute a material change of use. The court gave the example, the reporter related, of the introduction of a specialist gas-bottle disposal facility in an existing scrapyard. An increase in scrapyard noise does not by itself amount to a material change of use, but the different and additional noise impact of the bottle facility might be evidence of its being a materially different use.
The reporter also made reference to Childs v First secretary of State and Test Valley Borough Council , cited by the inspector in More of the same.
Section 4.327 of DCP Online deals with intensification.