In McGaw v Welsh Ministers (2021) EWCA Civ 976 the Court of Appeal states that the General Permitted Development Order exists in order to relieve developers of the regulatory burden of applying for planning permission in categories of case defined in such a way that it can be seen that such permission ought to be granted, and to relieve planning authorities of the burden of dealing with such applications. The classes of cases to which the GPD Order applies are defined so as to set out the parameters for the grant of general permissions while protecting various concerns relevant to planning concerns, including height restrictions and visual amenity and restrictions to limit what can be seen from the highway. The Court of Appeal says, at para 17, that the GDP Order should be approached in the light of its statutory purpose.
Both the words that set out what is permitted and those that limit the scope of the permission should be read in a “broad and common sense way” according to the “ordinary meaning” of the language used.