This is a simple point, that a development can only rely on permitted development rights to the extent that it falls squarely within the boundaries (including restrictions and limitations) of that right both in terms of the form of the development and its purpose.
The telephone box mystery
A largely town centre phenomenon has been the re-birth of the telephone box. The distinctive red phone boxes having been turned into community libraries, defibrillator storage points and the like, people have been genuinely surprised to see new telephone kiosks appearing on their high streets. This is doubly-strange in a world where almost every person over the age of about eight carries a mobile phone.
The mystery is solved when one considers that the value of a modern phone box is not in the provision of a means of electronic communications (the purpose for which the Permitted Development right exists) but rather in the provision of illuminated advertising space. This was the issue in New World Payphones Ltd v Westminster City Council  EWCA Civ 2250.
The decision of the Council, and the Court
The Council had rightly (according to the Court of Appeal) refused prior approval for the proposed kiosk on the basis that it would add to clutter on the high street and wasn’t necessary. The developer subsequently persuaded an Inspector otherwise and that it was a legitimate use of the right. The High Court then supported the developer but the Court of Appeal has now found, in effect, for the Council.
Permitted development rights
The Court of Appeal’s judgement serves as a useful reminder that in order to rely on permitted development rights, the whole of the proposed development must fall within the scope of the relevant class within the Permitted Development Order. It is not sufficient that one part or some part of it would be within that scope. Particularly in this case (but relevant elsewhere) a mixed use or dual purpose development where one part falls outside the scope of a particular class will not be permitted development. Important too, the courts will look at the purpose for which a right was conferred when considering whether a particular development or proposal does or don’t benefit.