This is just a very quick and unresearched response Paul, but Yes, I would say that they will qualify under most circumstances.
Although not written, as far as I can see, they are implied static domicilaries, and require planning permission for the most part. The question really arises over whether they are fed from hook-ups not classified as fixed or permanent supplies, or fixed services...
As I say - not entirely sure, but that's my quick thoughts!
Oh...spelling...spelling...
[This message has been edited by uksparky (edited 12-16-2004).]