The term ‘material change of use’ is not defined in the 1990 Act. Its meaning has to be ascertained, therefore, by reference to the many cases in which the courts have had to consider its significance. In Parkes v Secretary of State for the Environment [1978] 1 WLR 1308 (CA), Lord Denning MR said that ‘operations’ comprised activities which resulted in some physical alteration to the land, which had some degree of permanence to the land itself; whereas ‘use’ comprised activities which are done in, alongside, or on the land but which did not interfere with the actual physical characteristics of the land. Accordingly, he held that, for the purposes of serving a discontinuance order under what is now s 102 of the 1990 Act, the sorting, processing, and disposal of scrap materials was a ‘use’ of land.