3.—(1) In this Act, “development” means, except where the context otherwise requires, the carrying out of any works on, in, over or under land or the making of any material change in the use of any structures or other land.
(2) For the purposes of subsection (1) and without prejudice to the generality of that subsection—
(a) where any structure or other land or any tree or other object on land becomes used for the exhibition of advertisements, or
(b) where land becomes used for any of the following purposes—
(i) the placing or keeping of any vans, tents or other objects, whether or not moveable and whether or not collapsible, for the purpose of caravanning or camping or habitation or the sale of goods,
(ii) the storage of caravans or tents, or
(iii) the deposit of vehicles whether or not usable for the purpose for which they were constructed or last used, old metal, mining or industrial waste, builders' waste, rubbish or debris,
the use of the land shall be taken as having materially changed.
(3) For the avoidance of doubt, it is hereby declared that, for the purposes of this section, the use as two or more dwellings of any house previously used as a single dwelling involves a material change in the use of the structure and of each part thereof which is so used.