In determining whether a log cabin within the curtilage of a house in Kent fell within the definition of a caravan, an inspector has set out useful relevant legislation and case law (DCS Number 400-031-296). Here it is:-
Relevant legislative provisions:
Case law, in Wyre Forest BC v SSE & Allen’s Caravans , the inspector recorded, has established that it is necessary to consider whether a structure is a caravan by considering it in the light of the statutory definitions. Subsection 29 (1) of the Caravan Sites and Control of Development Act 1960 (CSCDA) says that a ‘caravan’ means any structure designed or adapted for human habitation, which is capable of being moved from one place to another (whether by being towed, or by being transported on a motor vehicle or trailer) and any motor vehicle so designed or adapted, but does not include (a) any railway rolling-stock, which is, for the time being, on rails forming part of a railway system or (b) any tent. Subsections 13 (1) and (2) of the Caravan Sites Act 1968 (CSA) defines a twin-unit caravan as follows: (1) a structure designed or adapted for human habitation which (a) is composed of not more than two sections separately constructed and designed to be assembled on a site by means of bolts, clamps or other devices; and (b) is, when assembled, physically capable of being moved by road from one place to another (whether by being towed, or by being transported on a motor vehicle or trailer), shall not be treated as not being (or as not having been) a caravan within the meaning of Part I of the CSCDA by reason only that it cannot lawfully be so moved on a highway when assembled.
It is a well-established principle, the inspector continued, that when considering whether or not a structure is deemed to be a caravan, the commonly applied ‘construction’ and ‘mobility’ tests should be considered. The following are relevant considerations; there has to be a structure, it has to be designed or adapted for human habitation and it must be capable of being moved as a single structure. A structure composed of not more than two separately constructed sections which are designed to be assembled on site, and, when assembled, is physically capable of being moved by road, is not excluded from the relevant legislative provisions.
Relevant case law:
In terms of the construction and mobility tests, the inspector noted the following case law. In the case of Byrne v SSE and Arun District Council  an enforcement notice was issued requiring the removal of a log cabin on the basis that it was to be treated as a caravan. On appeal, the enforcement notice was upheld but corrected on the basis that the log cabin was a structure which had involved the carrying out of building operations on the land. It was considered that the structure was not a caravan within the meaning of the relevant legislative provisions and so the period for the taking of enforcement action was four years (s171B (1)) and not 10 years. Mr Byrne applied to the High Court to have that decision quashed. The judge dismissed that application and held that the inspector’s conclusion that the cabin was not assembled on site out of two separately constructed sections (the construction test) was conclusive that s13 (1) (a) of the CSA did not apply and did not operate to deem the structure as a caravan. Furthermore, on a proper construction of s13 (1) (b) of the CSA (the mobility test), the phrase “when assembled” required mobility to be tested by reference to the circumstances of where and how the cabin had in fact been assembled and did not simply mean “in its assembled state”. As such the cabin did not fulfil the mobility test. It was noted that consideration had to be given to the practicality of moving the structure as part of the mobility test. In addition, in Brightlingsea Haven Ltd v Morris  it was considered that the test of mobility when assembled is that the structure must be physically capable of being towed on a road, or of being carried on a road, not momentarily but enough to say that it is taken from one place to another.
Turning to the appeal case before him, the inspector was satisfied on the evidence that the structure passed the mobility test. With regard to the construction test, however, it was not clear that there had been two units which were fully assembled prior to being joined. He determined that the structure failed to meet the construction test, concluding that it did not amount to a twin-unit caravan, as defined by the CSA.
DCP Online covers the legal definition of a caravan at section 4.353.