The basic guidelines were laid down in Cardiff [1949]:

• a ‘building’ or ‘structure’ will be something of such size that it would normally be built or constructed on site (as opposed to being brought in already made);
• it will have some degree of permanence. Once installed it will normally remain in situ and only be removed by pulling down or taking to pieces;
• whether or not the thing is physically attached to the site is relevant but is not conclusive;
• a limited degree of motion does not prevent it being a structure.

Applying this logic, it was held in Swansea [1993] that 27 self-build wooden chalets (resting on concrete pillars – but little more than sheds) were ‘buildings’. As far as polytunnels are concerned, an Inspector recently found that they were ‘buildings’ and that decision has been upheld by the High Court. Relevant factors included the height and width of the polytunnels which were linked together as a solid unit (there were 13 blocks of 24 polytunnels, giving them substantial size and proportion). They were fixed to the ground, using machinery, to a depth of 1m. As such, they had a substantial degree of physical attachment to the ground. Moreover, they remained in place for between three and seven months in any one year and were therefore not ephemeral. The tunnels could be removed – but only by taking them to pieces. As a matter of fact and degree they could be regarded as permanent.

This is clearly a decision that may prove highly significant. However, it was reached very much on its facts with much emphasis being placed by the parties on the intrusiveness into a particular location of beauty. It may therefore be that it does not apply more generally. But, there must now be stronger arguments that polytunnels in general do require planning permission (both for their erection and their subsequent removal). Presumably, the scale of the operation (ie the size of the polytunnel development) will be crucial, with the result that major growers may be more seriously affected than small farmers. Either way, there is now considerable uncertainty as to the planning legality of polytunnel structures. Hall Hunter v First Secretary of State [2006] EWHC 3482 (Admin). © Practical Lawyer