The crux of the case related to the fallback position that the appellants argued they could adopt. The tree house had already been erected under a mature tree some 15 metres from the main house. Firstly, the inspector held it could not be regarded under the exceptions to inappropriate development set out in paragraph 145 of the NPPF, as the appellants had argued. This was because the tree house did not constitute outdoor sport or recreation as it related to a domestic dwelling, it did not relate to an extension of the main house and could not be considered to constitute limited infilling as it abutted open fields.
In looking at the harm of the treehouse to loss of openness, however, he thought it had limited impact as it was contained under the canopy of the tree, was seen in the context of a residential setting and was screened from public view. Finally, the inspector considered other matters as to whether the treehouse could be justified. Here he accepted the appellants' argument that they had a workable fallback position of removing the treehouse from the tree and placing it on the ground under permitted development rights. The inspector considered this a reasonable prospect and also noted that an even larger structure could be built under permitted development rights. He concluded the treehouse was inappropriate development but there were special circumstances to justify its approval, with the consequential loss of openness being no greater than the realistic fallback position.
Inspector: David Fitzsimon; Written representations